Cosmetic surgeries are performed to change the appearance of people and improve their self-esteem, and according to available reports, Iran is ranked first in terms of the percentage of cosmetic surgeries performed. Therefore, this study aimed to predict the intention to undergo cosmetic surgery among female students of Hamadan University of Medical Sciences based on the reasoned action theory. This was a cross-sectional study conducted on 340 female students of Hamadan University of Medical Sciences selected by the random stratified sampling method in 2017. Data collection tools were demographic variables and the questionnaire that measured theoretical constructs of the reasoned action theory about cosmetic surgery. The questionnaire was completed by the participants through the self-reporting method. Data were analyzed by SPSS software (version 24; SPSS Inc., Chicago, IL, USA) using the independent t-test, 1-way analysis of variance (ANOVA), Pearson correlation, and linear regression. Students often obtained information about cosmetic surgery through the Internet (63.2%). Students obtained 45%, 66.4%, 49.2%, 77.5%, and 48.1% of acquired scores for behavioral beliefs, evaluations of behavioral outcomes, motivation for obedience, normative beliefs, and behavioral intention associated with cosmetic surgery, respectively. There was a positive and significant correlation between the constructs of the reasoned action theory. Among the studied constructs, motivation for obedience, evaluations of behavioral outcomes and behavioral beliefs had a significant role in explaining the behavioral intention variance. Considering the role of the constructs of the reasoned action theory and the motivation for obedience in the formation of the process of intention to undergo cosmetic surgery, training by peer group can play an important role in reducing these pressures. Therefore, the formation of student cores under the supervision of academic associations of universities and the training of these cores for the transfer of information and skills to peer groups is recommended.