BACKGROUND: Large HIV care programs frequently subsidize antiretroviral (ARV) drugs and CD4 tests, but patients must often pay for other health-related drugs and services. We estimated the financial burden of health care for households with HIV-infected adults taking antiretroviral therapy (ART) in Côte d'Ivoire. METHODOLOGY/PRINCIPAL FINDINGS: We conducted a cross-sectional survey. After obtaining informed consent, we interviewed HIV-infected adults taking ART who had consecutively attended one of 18 HIV care facilities in Abidjan. We collected information on socioeconomic and medical characteristics. The main economic indicators were household capacity-to-pay (overall expenses minus food expenses), and health care expenditures. The primary outcome was the percentage of households confronted with catastrophic health expenditures (health expenditures were defined as catastrophic if they were greater than or equal to 40% of the capacity-to-pay). We recruited 1,190 adults. Median CD4 count was 187/mm(3), median time on ART was 14 months, and 72% of subjects were women. Mean household capacity-to-pay was $213.7/month, mean health expenditures were $24.3/month, and 12.3% of households faced catastrophic health expenditures. Of the health expenditures, 75.3% were for the study subject (ARV drugs and CD4 tests, 24.6%; morbidity events diagnosis and treatment, 50.1%; transportation to HIV care centres, 25.3%) and 24.7% were for other household members. When we stratified by most recent CD4 count, morbidity events related expenses were significantly lower when subjects had higher CD4 counts. CONCLUSIONS/SIGNIFICANCE: Many households in Côte d'Ivoire face catastrophic health expenditures that are not attributable to ARV drugs or routine follow-up tests. Innovative schemes should be developed to help HIV-infected patients on ART face the cost of morbidity events.