The unstimulated nitroblue tetrazolium (NBT) test for infection was studied in 139 patients with various dermatoses and in 100 healthy controls. Leukocytes from controls showed a mean NBT response of 6.3% ± 5.5%. In comparison to controls, patients with cutaneous infections had elevated NBT values, but no statistically significant difference (P=> .05) was found in the mean NBT values of patients with bacterial (37.9% ± 27.5%) and viral (32.5 ± 25%) dermatoses. Elevated NBT tests were found in patients with allergic vasculitis, erythema multiforme, and several other noninfectious dermatoses. The unstimulated NBT test is of limited value as a diagnostic aid for detecting infection in patients with dermatologic disorders.