Urine samples from the subjects internally contaminated with P-32 are collected, chemically processed, and measured beta activity by the liquid scintillation counting system of ALOKA-LSC-61 00. Then, effective doses are calculated by using the specialized software of MONDAL3.O. The results are applied in dosimetry for the radiation workers in the Nuclear Research Institute. Besides, this method is also compared with that of using GM counter, and the result is shown it gives sensitivity and accuracy better in the case of subjects contaminated at low activity level.