SummaryThe effect of chloroquine stimulation on the motility of porcine sperm stored for 6 h and on the subsequent conception rate was assessed. There was a drastic decline in sperm motility after 6 h storage at 4° and 25°C and a concomitant depression in their conception rate. However, chloroquine stimulation restored these functions towards normal, especially in sperm stored at 25°C. These observations, coupled with the stability of the litter size, regardless of treatment, suggest that chloroquine can be used in an artificial insemination programme involving the utilization of semen several hours after collection and some distance away from the source of the ejacula