Difenamizole is a non-steroidal anti-inflammatory drug and analgesic of the pyrazolone group related to metamizole. Mice given difenamizole per os showed maximal anti-nociceptive activity 30--60 min after administration. Difenamizole may depress the release of catecholamines from monoaminergic neurons. The analgesic action of difenamizole was antagonized by intracerebral injection of dopamine but not by norepinephrine. An analgesic action of difenamizole may be related to the dopaminergic system and difenamizole may depress the release of dopamine in the striatum, therefore, difenamizole may demonstrate an analgesic action following depression of dopaminergic neuronal activity in the striatum and preventing the binding of dopamine with the receptors.