Neutropenia in children and adults with HIV infection is frequently observed, perhaps as a result of impaired myelopoiesis, drug myelotoxicity, immune destruction, or opportunistic infection. The presence of antineutrophil antibodies (granulocyte antibodies, Gran Ab) has been associated with severe neutropenia, but the data are conflicting, and such antibody assays can be confounded by the presence of immune complexes and HLA antibodies. To determine both the prevalence of Gran Ab in children with HIV and whether such antibodies were related to neutropenia, we screened all HIV-infected children enrolled in our program (n=30, ages 1.5-17.5y) by performing granulocyte immunofluorescence (GIF), granulocyte agglutination (GA), and lymphocytotoxic HLA (LC) antibody assays. Reactivity was graded by a standard numeric score calculated per number of reactive cells. Of the 30 samples analyzed, 4 were indeterminate (could not distinguish between Gran Ab and HLA antibodies) and were excluded, yielding 26 evaluable samples. Of these, 12 (46%) were positive by GIF assay, and 7 (27%) were positive by GA assay. Six more samples were weakly positive by GA or GIF and strongly positive by LC, or were strongly positive by LC alone, indicating confounding HLA antibodies. Using the combined results of GA, GIF, and LC assays, 16 (62%) children had Gran Ab, 6(23%) had HLA Ab, and 4 (15%) were negative. There was no correlation between presence of Gran Ab and degree of neutropenia: 12/16 children with Gran Ab had an absolute neutrophil count (ANC) >1500/μL. We conclude that: 1) Gran Ab are highly prevalent in children with HIV infection; and 2) Gran Ab positivity does not correlate with the degree of neutropenia. Thus, antineutrophil antibody determination as currently performed does not appear to be useful in the evaluation of the HIV-infected neutropenic child.