BACKGROUND Thyroid hormone abnormalities have been reported elsewhere in human immunodeficiency virus-1 (HIV-1)-infected individuals, but such studies in Nigerians are scarce in literature. OBJECTIVE To evaluate thyroid function in HIV-1-infected individuals and to correlate thyroid function parameters with cluster of differentiation (CD4+) cell count. METHODS Total thyroxine (T4), total triiodothyronine (T3), thyroid-stimulating hormone (TSH), and CD4+ were estimated in 100 HIV-1-positive individuals on highly active antiretroviral therapy (HAART), 100 HIV-1-positive HAART naïve, and 100 HIV-1-negative controls. The mean values were compared between the groups, and CD4+ cell count was correlated with measured thyroid hormones. RESULTS Thyroid function abnormalities were seen in 52 HIV-1-positive individuals on HAART and 56 individuals without HAART treatment. The pattern of thyroid hormone abnormalities is similar in both groups. Among the individuals on HAART, 10 had subclinical hypothyroid, 42 sick euthyroid, and 48 had normal thyroid hormones levels. Similarly, among those without HAART therapy, seven had subclinical hypothyroid, 49 sick euthyroid, and 44 had normal thyroid hormones levels. The HIV-1-positive individuals had significantly lower (P < 0.001) CD4+ cell count, TSH (P < 0.05), T3 (P < 0.01), and T4 (P < 0.001) when compared with controls. On the other hand, HIV-1-positive individuals on HAART had significantly higher (P < 0.01) CD4+ cell count and lower (P < 0.05) T4 levels than the HAART naïve group. CD4+ correlated positively with T4 in HIV-1-positive individuals on HAART (r = 0.26; P = 0.016) and HAART naïve (r = 0.218; P = 0.038). There was no significant correlation between CD4+ and measured thyroid hormones in the control individuals. CONCLUSIONS Asymptomatic thyroid hormone abnormalities are common in HIV-infected individuals, and these abnormalities are independent of whether the individuals were on HAART or without HAART treatment.