The aim of the study was to identify high-risk groups and the determinants of late HIV diagnosis in France in the era of highly active antiretroviral therapy (HAART), from January 1996 to June 2005. Informations were collected from an electronic medical record of all HIV- 1-infected patients who sought care in six HIV reference centers in France, constituting a prospective multicentric cohort. Patients were defined as "late testers" if they had presented with either symptoms of clinical AIDS or a CD4 cell count less than 200/mm(3) during the year of diagnosis, as "nonlate" if their CD4 count was above 200, and as "unknown" if CD4 cell count in the year at the time of diagnosis was not documented. Among the 4516 patients available for analysis, the percentage of late testing was 38% (n = 1718) and decreased after 2003 (31.5% in 2004-2005). This percentage was higher in heterosexual men (48.2%) than in homosexual men (31.7%) or heterosexual women (32.6%) and was higher for patients older than 30. Heterosexual men living in a couple with children had a higher risk of late testing (odds ratio [OR] = 1.65, 95% confidence interval [CI]: 1.03 to 2.66), while heterosexual women in a couple without children had a lower risk (OR = 0.46, 95% CI: 0.25 to 0.83). Among homosexual men, unemployment was associated with late testing (OR = 2.23, 95% CI: 1.14 to 4.36). The proportion of late testing was still high. Groups classically identified as low risk for HIV infection, particularly heterosexual men in a couple with children, were found to be at high risk for late testing. It seems necessary to improve HIV testing policy in the heterosexual population.