Background In adults, HIV increases the risk of certain cancers known, or thought, to have an underlying infectious etiology; the impact on the risk of cancer in children is less clear. Methods Here, we report results of an on‐going study at four pediatric oncology centers in South Africa in which children diagnosed with cancer are tested routinely for HIV. Odds ratios (OR) for the prevalence of various malignancies were calculated (with adjustment for age, sex, and center) for the children infected with HIV using all children with cancer and non‐malignant conditions, but not infected with HIV, as a comparison group. Results Of 882 children with cancer, 38 were HIV infected (for 12 the HIV status was unknown). HIV was associated with Kaposi sarcoma (all 10 cases were HIV infected; P < 0.001) and with Burkitt lymphoma (OR = 46.2, 95% confidence interval (CI) 16.4–130.3; 13/33). For non‐Burkitt non‐Hodgkin lymphoma (NHL), 2/39 were HIV infected (OR = 5.0, 95% CI 0.9–27.0). No other cancer type was significantly associated with HIV, including lymphoid leukemias (OR = 0.4, 95% CI 0.04–2.9; 1/172). Conclusions Only Kaposi sarcoma and Burkitt lymphoma were significantly associated with HIV infection although results for non‐Burkitt NHL were suggestive. Notably, we did not identify an association between infection with HIV and lymphoid leukemias, for which an underlying infectious etiology has been suggested. Pediatr Blood Cancer. 2011;56:77–79. © 2010 Wiley‐Liss, Inc.