PURPOSE: To measure the capability of heat (60 degrees C for 10 hr) and low pH to inactivate BVDV (a model of HCV) in human intravenous immunoglobulins. MATERIALS AND METHODS: The study was carried out on three batches of immunoglobulins produced by the Cohn method and contaminated with a known amount of BVDV. These mixtures, with and without 33%2sorbitol, were submitted to heat treatment at 60 degrees C for 10 hours. The same immunoglobulin batches were manufactured at pH 4.25 and 4.5 and stored at 4 degrees C and 4 degrees C and 21 degrees C for 28 days. Samples of the two experiments were taken at the beginning and the end. The viral infectiousness was calculated by the standard microtiration method in 96-well plates, using the CPE, and the reduction factor was measured for each experiment. RESULTS: Complete viral inactivation was achieved with the heat treatment after 4 hours, and the 33%2sorbitol decreased the formation of aggregates. Treatment by pH 4.5, at 21 degrees C for 28 days, decreased the viral load by approximately 2 log; no viral inactivation was achieved in samples stored at 4 degrees C. CONCLUSION: Heat is an effective method for inactivating HCV in final batches of human intravenous immunoglobulins when 33%2sorbitol is added. The use of low pH at 21 degrees C as a method of viral inactivation must be evaluated case by case, since, according to the present results, it only achieved a 2 log inactivation.