In this study we explored the prevalence of regret following uncommitted sexual encounters (i.e., casual sex that occurs with someone once and only once or with someone known for less than 24 hours) among 138 female and 62 male Canadian university students, who were approximately 21 years of age. The majority of participants self-reported that they had experienced feelings of regret after an uncommitted sexual encounter. We found women reported feeling significantly more regret than men. However, men's regret was more closely tied to physical attributes than women's regrets. Regret was also influenced by the quality of the sex: high-quality sex rarely led to regret, while the reverse was true for poor-quality sex. In keeping with past studies, intoxication by alcohol and/or drugs was often listed as a source of regret by both men and women.