Abstract: Nine random primers were used to amplify genomic DNA with randomly amplified polymorphic DNA （RAPD） methods in 3 inbred strains of rats. The result showed that the amplified band patterns of every individuals were same in one strain，the 3 strains of rats were homogeneous at these RAPD markers, however, the amplified band patterns showed different among three strains. The similarities between Wistar arid WKY, Wistar and F344,WKY and F344 were 87. 9%、98.5% and 89.2% respectively. The result indicated that the RAPD technique can be used as a method to monitor genetic contamination in inbred rats and to distinguish different strains of rats.