Summary Marine biotoxins are thermostable, mostly non‐protein molecules with different chemical components. According to solubility, they are divided into water‐soluble (hydrophilic) and fat‐soluble (lipophilic). The regulations of the EU and the Republic of Croatia regarding the maximum limits (ML) in live shellfish cover several groups: azaspiracids (AZA), okadaic group (okadaic acid and dinophysistoxins), yessotoxins (YTX), domoic and epi‐domoic acid (DA) and paralytic toxins (PSP). Lipophilic toxins (LT) of the okadaic group and azaspiracids cause poisoning manifested by symptoms of the digestive system, such as nausea, vomiting, spasm and diarrhea. Symptoms appear as early as 30 minutes to several hours after consuming contaminated shellfish and last approximately for three days. Yessotoxins are lipophilic marine biotoxins that have not been proven to cause human poisoning, however, when applied to experimental animals intraperitoneally, they show a high toxic effect (EFSA, 2009a). The same applies to pectenotoxins (PTX) for which acute reference doses (ARfD) have been determined (EFSA, 2009b), but are no longer covered by EU and Croatian regulations related to ML. Hydrophilic marine biotoxins (HT) are the neurotoxins domoic (DA) and epi‐domoic acid, and a group of paralytic marine biotoxins that can cause serious poisoning in humans, sometimes with a fatal outcome. DA poisoning causes gastrointestinal symptoms, but also neurological symptoms such as disorientation, confusion, behavioral changes, headache, convulsions and coma (Todd, 1993; Perl et al., 1990). In the most severe cases, muscle paralysis and suffocation occur, and death occurs due to suffocation due to respiratory paralysis and collapse of the cardiovascular system, usually within twelve hours (Prakash et al., 1971). Marine biotoxins accumulate in shellfish, and as they are thermostable, the harmful effect on human health is manifested acutely, after consumption, in the case when they are present in shellfish in concentrations where they can have a harmful effect on health. Cases of human poisoning are often not reported to the competent health institutions, because although unpleasant, they mostly pass without the need for medical intervention. For this reason, one gets the impression that cases of poisoning by marine biotoxins are extremely rare. In the Republic of Croatia, continuous monitoring of marine biotoxins in shellfish has been carried out for years. The following types of shellfish are sampled: mussels (Mytilus galloprovincialis), clams (Venerupis decussata), oysters (Ostrea edulis), queen scallops (Aequipecten opercularis), smooth clam (Callista chione) and warty venus (Venus verrucosa). This scientific opinion represents the results of the monitoring carried out between 2017 and 2022 for the group of amnesic marine biotoxins (ASP), for the group of azaspiracids (AZA), for the group of marine biotoxins of okadaic acid (OA), for the group of paralytic of marine biotoxins (PSP) and for the group of yessotoxins (YTX). In order to determine the actual exposure of consumers to marine biotoxins from shellfish, the calculation of average values for the UB, MB, LB scenario and for the highest concentration was used, which were combined with the highest intake of shellfish, which was calculated according to food consumption data in the Republic of Croatia that were collected in 2011/12 years. In addition, the exposure was assessed in the case of the assumption that shellfish contain the maximum legally permitted amount (ML), as well as the case with the corrected portion size due to the possible influence of heat treatment on the concentration of marine biotoxins, and the portion size of 400 g used by EFSA when preparing of its scientific opinions, in which it established current acute reference doses (ARfD) for each of the marine biotoxins monitored. An exposure assessment for AZA was not made because this marine biotoxin was not detected in any sample during the monitored time in an amount above the limit of detection/quantification (LOD/LOQ). Therefore, it can be concluded that the risk for consumers in this case is negligible. An exposure assessment for ASP in the assumed case of consumption of the proposed EFSA portion and in the case of a concentration equal to the NDK value, may lead to an intake of ASP that exceeds the ARfD value. ASP was quantified in some samples, but none had a concentration equal to or higher than ML. Therefore, the risk in this case can be considered negligible. The exposure assessment for OA indicates the possibility of intake of OA greater than the ARfD in certain cases, the most certain of which is the case of the highest concentration and consumption of the largest portion in the Republic of Croatia for mussels, which means that there is a risk for consumers. The concentration for OA, in addition to being found above the LOD/LOQ, was also found to be above the ML in 2.22% of mussel samples, 0.62% of oyster samples and 0.15% of scallop samples. The exposure assessment for PSP indicates the possibility of intake of PSP higher than the ARfD in certain cases, the most certain of which is the case of the highest concentration and consumption of the largest portion in the Republic of Croatia for mussels, which means that there is a risk for consumers. The concentration for PSP, in addition to being above the LOD/LOQ, was also above the ML in 0.51% of mussel samples and 0.31% of scallop samples. The exposure assessment for YTX did not lead to YTX intake exceeding the ARfD value in any case. YTX was quantified in some samples, but none had a concentration equal to or greater than ML. Therefore, the risk in this case can be considered negligible. When interpreting the results of this scientific opinion, it must be taken into account that the samples analyzed for marine biotoxins were collected directly from the shellfish breeding/harvesting areas for monitoring purposes. It's important to note that these shellfish weren't placed on the market, meaning consumers weren't exposed to marine biotoxins from these samples. This underscores the purpose and justification of the currently conducted extensive monitoring programme. Furthermore, recommendations for its continuation have been made, with certain improvements suggested.