The International Index of Erectile Function (IIEF) has been widely used to measure gay men's erectile functioning. However, the IIEF was initially developed using a sample of men whose sexual orientation was unspecified. Using scales not validated for specific populations can result in inaccurate assessments. The purpose of the current study is to evaluate the dimensionality, reliability, and validity of the IIEF with a large sample of gay men. One thousand and eighteen men self-identifying as "exclusively gay" completed an online survey consisting of demographics, IIEF, Hospital Anxiety and Depression Scale (HADS), Perceived Stress Scale 4 (PSS4), and Gay Male Sexual Difficulties (GMSD) erectile difficulties sub-scale. The replicability of the IIEF factor structure with a gay male sample was determined using exploratory and confirmatory factor analyses. Additionally, the HADS, PSS4, and GMSD were used to determine the validity of the IIEF. The current study was unable to replicate the IIEF factor structure. Four items required deletion and the factor solution differed from the original. Thus, reinterpretation of the latent variables was deemed necessary. Although the resultant 12item IIEF evidenced model fit, validity, and reliability it is not recommended for use with samples of gay men. The revised IIEF is unable to accurately measure gay men's erectile functioning as the content of the items fail to capture their sexual behaviours (i.e., insertive and receptive anal sex).