Ten widely used pharmaceutical agents for which mutagenicity or carcinogenicity data are still lacking were tested in parallel with three methods: Ames' bacterial mutagenicity test (TA1535, TA1537, TA98, and TAlOO Salmonella strains), micronucleus (mice BDF,), and sperm morphology abnormality (mice) tests. The groups and generic names of the tested products, all produced by Pharmachim (Bulgaria), were as follows: Psychopharmaca (Loxapinsuccinate, Medazepam hydrochloride, Nomifensinmaleate, Viloxazine hydrochloride), Vasodilatators (Nitroprussid Na, Isosorbid mononitrate, Isosorbid dinitrate), Spasmolytica (Trimetoquinol), Antirheumatica (Diclofenac Na), and the antimycotic agent Lavendotricin. In all testa, negative results were obtained. To avoid false negative results, several suggestions are made.