Abstract: Frozen section specimens with a thickness of 4 μm were made from adult worms of An-giostrongylus cantonensis in order to detect the serum antibodies in rats infected with An-giostrongylus cantonensis by indirect fluorescent antibody test (IFAT). The results showed that the positive rates of the serum samples 2 and 4 weeks after infection were 92. 0%(46/ 50) and l00% (19/19), respectively. The results of serum samples in healthy rats and normal saline (as control) were negative. This technique proved to have a highly detectable rate and the positive reaction might occur in early infection. It might be used for the early supplementary diagnosis of angiostrongyliasis.