The repeatability of male wing-beat frequency measurements of Anopheles quadrimaculatus was determined by using mosquitoes allowed free flight in a confined space. Heritability of the wing-beat frequency trait was estimated for a laboratory and a wild-strain population of An. quadrimaculatus by using free-flight measurement with a parent-offspring regression of offspring on dams. Repeatability was 0.75 for free flight. Wing-beat frequency rose for the 1st day after adult emergence and then became steady. Female heritability of wing-beat frequency was 21.6% for colony and 24.0% for wild-strain mosquitoes. Male heritability was 57.2% for colony and 53.7% for wild-strain mosquitoes. Male heritability was significantly different from 0 when probabilities were combined across both populations.