Low maternal vitamin D has been associated with preterm birth (PTB). Human immunodeficiency virus (HIV)-infected pregnant women are at risk for PTB, but data on maternal vitamin D and PTB in this population are scarce.  In a cohort of Latin American HIV-infected pregnant women from the National Institute of Child Health and Human Development International Site Development Initiative protocol, we examined the association between maternal vitamin D status and PTB. Vitamin D status was defined as the following 25-hydroxyvitamin D levels: severe deficiency (< 10 ng/mL), deficiency (10-20 ng/mL), insufficiency (21-29 ng/mL), and sufficiency (≥30 ng/mL). PTB was defined as delivery at < 37 weeks' gestational age (GA). Logistic regression was used to assess the association between maternal vitamin D status and PTB.  Of 715 HIV-infected pregnant women, 13 (1.8%) were severely vitamin D deficient, 224 (31.3%) were deficient, and 233 were (32.6%) insufficient. Overall, 23.2% (166/715) of pregnancies resulted in PTB (median GA of PTBs = 36 weeks [interquartile range: 34-36]). In multivariate analysis, severe vitamin D deficiency was associated with PTB (odds ratio = 4.7, 95% confidence interval: 1.3-16.8]).  Severe maternal vitamin D deficiency is associated with PTB in HIV-infected Latin American pregnant women. Further studies are warranted to determine if vitamin D supplementation in HIV-infected women may impact PTB.