Objective:to analyze the factors associated with inconsistent use of male condoms among HIV-negative men who have sex with other men.Method:a cross-sectional, analytical and nationwide study conducted online in all the Brazilian regions in 2020, via networks and in dating websites. Inconsistent condom use was defined as occasional use or as never using it. Descriptive statistical analyses were performed, as well as association and binary logistic regression tests.Results:inconsistent condom use was reported by 1,222 (85%) of all 1,438 participants. The “homosexuals” (ORAdj: 2.03; 95% CI: 1.14-3.59;p=0.016), “having a fixed partner” (ORAdj: 2.19; 95% CI: 1.55-3.09;p<0.001), “oral sex” (ORAdj: 2.41; 95% CI: 1.31-4.43; p=0.005), “insertive anal” (ORAdj: 1.98; 95% CI: 1.10-3.58;p=0.023) and “STI diagnosis” (ORAdj: 1.59; 95% CI: 1.13-2.24;p=0.007) variables were independently associated with inconsistent use of male condoms. The “receiving advice on HIV test from a friend” (ORAdj: 0.71; 95% CI: 0.52-0.96;p=0.028) and “sex worker” (ORAdj: 0.26; 95% CI: 0.11-0.60;p=0.002) variables were protective factors.Conclusion:the variables under study pointed to a strong relationship between steady partners and increased trust and low adherence to condom use, corroborating other studies.