To evaluate the technical and behavioral impact of predonation alanine aminotransferase (ALT) testing, one group of 2914 donors (Reflotron group) were tested with the Boehringer Mannheim Reflotron instrument; 3042 control group donors had no predonation test. Mobile blood collection sites in three regional blood centers were studied. More Reflotron group donors than control group donors thought that predonation testing did not add time and was a good idea. Both groups were equally satisfied with the donation process and indicated they would donate again even if testing added time. Comparison of the Reflotron and standard laboratory tests showed excellent correlation with low variability. The mean r value was 0.934, with a mean sensitivity of 94.4 percent and a specificity of 99.8 percent. The staff working with the Reflotron group found predonation testing easy to incorporate into donor screening. They observed that donors were pleased with testing and accepting of deferral counseling for elevated ALT. The control group staff was concerned that predonation testing would require more time and would have a negative effect on the donor return rate. This did not appear to be the case as judged by donor response and the 6-month return rates of 50 percent for Reflotron group and 54 percent for control group donors.