Recent human studies support historical animal studies that suggested an association between peripheral blood monocyte:lymphocyte (ML) ratio and tuberculosis (TB) disease. To evaluate generalizability of this finding, we modeled the association between peripartum ML ratio and incident TB disease within 18 months postpartum among 1202 HIV-infected women in South Africa, Tanzania, Uganda, and Zimbabwe. The ML ratio was associated with increased risk of TB disease independently to combination antiretroviral therapy, World Health Organization stage, or CD4 count (adjusted hazard ratio = 1.22, 95% confidence interval: 1.07 to 1.4, P = 0.003 per 0.1 unit increase in ML ratio).