Abstract: Consent forms required by Institutional Ethics Review Boards have changed historically to protect universities and participants but may inadvertently affect sex research through the provision of detailed warnings. We tested this contention using an experiment (N = 135) and a survey (N = 75). Three types of consent forms were used to manipulate the degree of warning ("procedures only," "mild warnings," "explicit warnings"). We measured participants' mood and expectations after reading the consent form but prior to any study tasks. Following the study, we assessed post-test mood and participants' expectations and experience in the study. Consent forms did not affect mood or survey data. However, warnings influenced participants' evaluations of experimental stimulus materials, with more negative evaluations produced by warnings and detailed content than by procedures only wording. Moreover, more detailed content in consent forms did not provide participants with a better sense of what the studies would entail. We discuss the need to provide information to participants while minimizing demand effects. Key words: Research ethics review, consent forms, bias, REB requirements.