Presence of antibodies to RV 3 and RV 5 was tested by HIT and NT in 60 human sera. Antibodies to RV 3 were detected in 23 sera by HIT in a titre range of 1:4--1:64 and in 19 sera by NT in a titre range of 1:4--1:256. Antibodies to RV 5 were detected in 31 sera by HIT in titres of 1:4--1:268 and 27 sera by NT in the same titre range. In a group of 22 persons with unequivocal serum antibodies nasal secretory antibodies were found in 11 subjects in titres of 1:4--1:32. In a group of 16 persons without detectable serum antibodies, presence of secretory antibodies (titre 1:4) was only found in four cases.