The paper presents the findings of the first large-scale survey on post-mortem organ donation among the general Slovenian population. It focuses on the reported donation willingness, the barriers to joining the register of organ donors and the position towards consent to donate organs of deceased relatives. A face-to-face survey was conducted on a probability sample of 1,076 Slovenian residents between October and December 2017. The performed analyses included estimations of means and proportions for target variables, an evaluation of between-group differences and a partial proportional odds model to study the relations between organ donation willingness and socio-demographic characteristics. The mean reported willingness to donate one's own organs after death was 3.77 on a 5-point scale, with less than a third of respondents claiming to be certainly willing. Only 6% of those at least tentatively willing to donate organs were certain to join the register of organ donors in the future. The most frequently reported barriers to registration were unfamiliarity with the procedure and a lack of considering it beforehand. The reported willingness to donate organs of a deceased relative strongly depended on the knowledge of the relative's wishes, yet 80% of the respondents did not discuss their wishes with any family members. The findings confirm the gap between the reported donation willingness and joining the register of donors. Future post-mortem organ donation strategies need to consider socio-demographic and attitudinal factors of donation willingness and help stimulate the communication about organ donation wishes between family members.