BackgroundNigeria has a high burden of HIV and tuberculosis (TB). To reduce TB-associated morbidity and mortality, the World Health Organization recommends that HIV-positive TB patients receive antiretroviral therapy (ART) within eight weeks of TB treatment initiation, or within two weeks if profoundly immunosuppressed (CD4<50 cell/μL).MethodsTB and HIV clinical records from facilities in two Nigerian states between October 1st, 2012 and September 30th, 2013 were retrospectively reviewed to assess uptake and timing of ART initiation among HIV-positive TB patients. Healthcare workers were qualitatively interviewed to assess TB/HIV knowledge and barriers to timely ART.ResultsData were abstracted from 4,810 TB patient records, of which 1,249 (26.0%) had HIV-positive or unknown HIV status documented, and the 574 (45.9%) HIV-positive TB patients were evaluated for timing of ART uptake relative to TB treatment. Among 484 (84.3%) HIV-positive TB patients not already on ART, 256 (52.9%, 95% CI: 45.0–60.8) were not initiated on ART during six months of TB treatment. 30.0% of 273 patients with a known CD4≥50cells/μL started ART within eight weeks, and 14.8% of 54 patients with a known CD4<50cells/μL started within the recommended two weeks. Only 42% of health workers interviewed reported knowing to interpret guidelines on when to initiate ART in HIV-positive TB patients based on CD4 cell count results. CD4 cell count significantly predicted timely ART uptake.ConclusionA large proportion of HIV-positive TB patients were not initiated on ART early or even at all during TB treatment. Retraining of staff, and interventions to strengthen referral systems should be implemented to ensure timely provision of ART among HIV-positive TB patients in Nigeria.