Pharmacological studies with 6-cyclohexyl-1-hydroxy-4-methyl-2 (1H)-pyridone, 2-aminoethanol salt (ciclopiroxolamine, Cic, Hoe 296, Batrafen) have been carried out in various test animal species and in isolated organs. The studies did not reveal any indication of effects on the central nervous system or an metabolic functions such as body temperature, urinary and biliary excretion, blood coagulation and acute inflammatory processes. Blood pressure and heart rate were slightly decreased. In the isolated ileum of the guinea pig, slight antagonism towards Ba2+, histamine, carbachol and nicotine was observed. With the doses of ciclopiroxolamine used in local therapy, no systemic pharmacological effects can be expected. Short-term toxicity studies carried out in the usual species of test animals produced oral LD50 values in the range of g/kg of body weight. A 4-week oral administration of 30 mg/kg body weight was virtually symptom-free and the corresponding dose in a 3-month administration was 10 mg/kg. The compound revealed a favourable therapeutic index. As anticipated, the cutaneous tolerance was dependent on animal species, pharmaceutical preparation, concentration of pure drug and duration of the application. The same applies to the tolerance in the vaginal mucosa of the dog. Studies on reproduction toxicology, mutagenicity, carcinogenicity and phototoxicity of ciclopiroxolamine produced no prohibitive findings.