The effect of 12 derivatives of N-phenyl-N′-aryl- or alkylthiourea, inhibitors of human enteroviruses and foot-and-mouth disease virus, on reproduction of some rhinoviruses (H-17, B-632) in HeLa Bristol cells was studied. As screening methods both the multicycle growth test in roller tube cultures and two variants of plaque inhibition tests were employed. The compounds selected were tested in one-step growth cycle set-up. We established that N-phenyl-N′-4-hydroxyphenyl-thiourea (V-24) and N-phenyl-N′-2-carboxyphenylthiourea (V-17) have a distinct inhibitory effect on the growth of rhinovirus H-17, and N-phenyl-N′-2-hydroxy-5-nitrophenylthiourea (V-25) inhibited strongly the multiplication of rhinoviru