Males that present infrequently in parthenogenetic Artemia are commonly called "rare males". By rearing cloned parthenogenetic Artemia in the laboratory, the frequency of rare males was observed for seven Artemia populations with different ploidy compositions. The results showed that the values of the male:female ratio varied from 0.53:1000 to 1.40:1000 in diploids from different populations, and there were significant differences among populations and clones. No rare males were found in any of the 46 polyploid clones (217,197 individuals) observed.