Food (dietary) supplements include a wide range of products that are designed to be taken because of their added nutrients and presumed health benefits. Global food supplement sales are experiencing rapid growth and supplements that based on botanicals are among the most popular. The meteoric rise in sales coupled with the general lack of a commitment to pass effective regulation make this market more vulnerable to dishonest producers, increase the likelihood that supplements containing adulterants are sold on the market, and a greater prevalence of safety and quality issues (contamination by pesticides and mycotoxins). In this paper, we present an overview of various sample preparation and analytical techniques that can be used for the determination of bioactive substances in food supplements based on plant extracts and for making purity assessments of plant extracts in these preparations. The analysis looks at data collected from 2012 to 2017. The work is divided according to the different approaches taken when analysing food supplements and groups of bioactive substances found in plant extracts (purity assessments and the determination of bioactive substances). Display omitted •Analytical methods for quality control of food supplements based on plant extracts were reviewed.•Advantages and limitations of extraction techniques and separation methods were discussed.•Critical evaluations of the poor quality of food supplements were highlighted.•Adulterants, endocrine disruptors, pesticides and mycotoxins contamination were pointed out.•Perspectives in quality control of food supplements based on plant extracts were summarized.