Flies carrying the inactive mutation of Drosophila melanogaster have only 15% wild-type titers of the putative neurotransmitter octopamine. With a view to discovering whether the inactive mutation impairs learning, I describe the effect of the inactive mutation on experience-dependent courtship modification (EDCM). Wild-type males rapidly condition to immature males and modify their behaviour toward subsequent target flies. The weaker EDCM phenotype of inactive males is similar to that of dunce males. Using time-sampling, habituation is most rapid for wild-type males and slowest for dunce males, with inactive males showing an intermediate phenotype. These results support the notion that octopamine plays a significant role in the manifestation of Drosophila learning behavior.