Four staining methods for aspartate aminotransferase (AAT) detection after electrophoresis have been reported. Comparison of the minimum AAT activity detected by these methods showed the following sequence: Sakakibara et al.> Rej and Herder > Decker and Rau > Banks et al. Addition of ADP and diaphorase to the stain of Banks increased its sensitivity 10 fold. The presence of lactate dehydrogenase (LDH > activity in the samples gave electrophoretical artifacts when the methods of Banks et al. and Rej & HoSrder were used. These artifacts were due to the nothing dehydrogenase (NoDH) activity of LDH as demonstrated by chromatography on 5′ AMP-Sepharose 4B (LDH affinity support).