The use of the soluble antigen fluorescent antibody (SAFA) test for the laboratory diagnosis of trichinosis is described. Twenty-six of 28 specimens from humans with proven trichinosis and 2 of 90 specimens from healthy controls reacted in this test. Except for schistosomiasis, reactions with sera from individuals infected with other parasitic agents rarely occurred. Elution of dried blood specimens obtained on absorbent paper could be tested satisfactorily by this technic. Results with mice, rats, and rabbits experimentally infected with single and multiple doses of Trichinella spiralis larvae showed that SAFA antibodies could be detected 2 weeks after inoculation and reached a peak 4-5 weeks later. A high antibody titer was sustained until the end of the experiment, approximately 8 months after infection. © 1968.