Eight hundreds and fifteen patients of the Prof. Edgard Santos Hospital, Salvador, Bahia, were studied for G6PD deficiency by the spot test. The frequencies of deficients were 11,39% for the blacks, 7,85% for the dark mulattoes and 6,98% for the medium mulattoes. There was no difference in the percentage of deficients between out patients and patients in the wards. Also, there was no difference in the means for hematocrit, hemoglobin, frequency of hospitalization and type of disease between patients with the deficiency and the control patients. However, a past history for jaundice was significantly more frequent among the deficient patients (22,22%) than among the control patients (12,76%) (x 2(1) = 4,43; p less than 0,03). These results suggest that, in Northeastern Brazil, G6PD deficiency is not severe enough to require hospitalization but is able to cause clinically detectable jaundice.