Objectives: To describe the clinical and virologic characteristics of HIV-HBV coinfection, including the predictors of high maternal HBV viral load in pregnant women with HIV in sub-Saharan Africa (SSA). Methods: HPTN 046 was a HIV perinatal transmission clinical trial evaluating infant nevirapine vs. placebo. Women-infant pairs ( n = 2016) were enrolled in SSA from 2007 to 2010; 1579 (78%) received antiretrovirals (ARV). Maternal delivery samples were retrospectively tested for hepatitis B surface antigen (HBsAg), and if positive, were tested for hepatitis B e antigen (HBeAg) and HBV viral load (VL). High HBV VL was defined as ≥10 6 IU/ml. Results: Overall, 4.4% (88/2016) had HBV co-infection, with geographic variability ranging from 2.4% to 8.7% ( P < 0.0001); 25% (22/88) were HBeAg positive with prevalence in countries ranging from 10.5% to 39%. Fifty-two percentage (40/77) of those with HBV received ARV, the majority (97%) received 3TC as the only HBV active agent. HBeAg positivity was associated with high maternal HBV VL, odds ratio (OR) 37.0, 95% confidence interval (CI) 5.4-252.4. Of those with high HBV VL, 40% (4/10) were receiving HBV active drugs (HBV-ARV). HBV drug resistance occurred in 7.5% (3/40) receiving HBV-ARV. Conclusions: In SSA, HBV co-infection is common in pregnant women with HIV. HBsAg and HBeAg prevalence vary widely by country in this clinical trial cohort. HBeAg is a surrogate for high HBV viral load. HBV drug resistance occurred in 7.5% receiving HBV-ARV with lamivudine as the only HBV active agent. These findings reinforce the importance of HBsAg screening and early treatment with two active agents for HBV.