Some individuals seek to enhance their cognitive capabilities through the use of pharmacology. Such behavior entails potential health risks and raises ethical concerns. The aim of this study was to examine whether a precursor of behavior, ethical judgement towards the use of existing biological cognitive enhancers (e.g., coffee, legal and illegal drugs), is shaped by the perceived characteristics of these cognitive enhancers. Students and employees completed an online questionnaire which measured perceived characteristics of 15 substances presented as potential cognitive enhancers and a measure of ethical judgement towards these cognitive enhancers. Results of mixed model regression analyzes show that ethical judgement is more favourable when cognitive enhancers are perceived as being legal, familiar, efficient, and safe for users' health, supporting all hypotheses. Results further show that 36% of variance (in the null model) lies at the level of cognitive enhancers and 21% at the level of participants. In conclusion, cognitive enhancers vary widely in terms of ethical judgement, which is explained by the perception of the mentioned characteristics. Implications regarding prevention and policy-making are discussed.