Microparticle enzyme immunoassay (MEIA) for thyrotropin (TSH) was evaluated and results were compared with those of immunoradiometric assay (IRMA) procedure. Coefficient of variations of within day precision was 3.8-9.6% and those of between day precision was 3.6-17.2%. Correlation between the MEIA(Y) and two site IRMA(X) was excellent (Y=1.0445X-0.1538, r=0.9948). The sensitivity of the assay (mean+/-2 SD of the zero standard) was 0,0158 microIU/ml. The concentration measured in 497 healthy subjects were ranged from 0.2-3 microIU/ml (mean 1.37 microIU/ml, SD 0.59). Conclusively, MEIA is more fully automated than IRMA, well correlated with IRMA, can be reliable method for screening test of thyroid function.