Men who have sex with men (MSM) account for more than half of the new HIV diagnoses in Spain. This study aims to carry out a descriptive analysis of the sexual practices and frequency of condom use of MSM and identify the variables that explain inconsistent condom use during anal intercourse. The sample consists of 405 men between 18 and 60 years of age (M = 28.94; SD = 9.35). The results indicate that the percentage of consistent condom use is 72.9% for anal intercourse. Lack of risk perception, high self-esteem, and greater sensation-seeking are risk factors for risky sexual behavior. In contrast, high levels of sexual assertiveness and self-efficacy are protective factors. The proposed model explains between 33.8 and 49.2% of the variance. These findings highlight the importance of designing and implementing condom promotion programs for MSM who engage in anal intercourse with specific sections that consider the acquisition of assertive skills and reduce the risks associated with a perceived invulnerability to HIV.