We have previously found that genetic alterations in neuronal ion channel function have specific effects on learning and memory of a conditioned courtship behavior in Drosophila. Using a behavioral assay of conditioned odor avoidance, we report here that shaker mutants, in which potassium-channel function is abnormal, are defective in both their rate and maximum level of acquisition when compared to wild-type flies. napts (no action potential, temperature sensitive) mutants, in which nerve excitability is decreased due to faulty sodium-channel function, can achieve a normal (wild-type) level of learning, but the rate of acquisition is reduced. Neither the shaker nor the napts mutations affect memory decay following rest periods greater than 30 min. However, memory may decay more rapidly in both shaker and napts flies during the initial 30-min period following training. These results suggest that neuronal sodium- and potassium-channel function may be of general importance to the processes of acquisition and short-term memory in Drosophila.