Thin layer polyacrylamide gel electrophoresis was developed for analyzing alkaline phosphatase (ALP) isozymes by introducing 25mM N-methylglucamine as a medium, and demonstrated to have good resolution. The method enabled unequivocal characterization of ALP isozymes in combination with pre-treatment of specimens by heat treatment, sialidase digestion and WGA binding. In transient hyperphosphatasemia, ALP activities of both bone and novel liver-like types were markedly increased. The latter type of ALP was different from typical liver type in having a more anodic electrophoretic mobility and stronger affinity for WGA.