Abstract.Evidence for transmission of non‐A non‐B hepatitis (NANB) was sought in 41 patients with primary immune deficiency who were receiving human intravenous immune globulin (IGIV) over periods ranging from 6 to 15 months at a monthly dosage of 400 mg/kg body weight. One lot of a reduced and alkylated IGIV and three lots of a nonmodified preparation stabilized at pH 4.2 were used. No evidence of NANB was found, although transient elevations in serum glutamic pyruvic transaminase (alanine aminotransferase) were found in 6 of the patients. The possible causes of the elevated levels in these 6 patients are discus