Sexual selection is thought to result in an elongation of genitalia in insects. Part of the genitalia of the leaf beetle Lema (Lema) coronata Baly is approximately twice the body length in both sexes. Nine microsatellite loci were isolated from L. (L.) coronata for use in future studies on the correlation between genital length and reproductive success. The nine loci were polymorphic, with three to six alleles per locus recorded in 40 individuals. Observed heterozygosity ranged from 0.08 to 0.38 and expected heterozygosity from 0.51 to 0.75. The non-exclusive probability of the second parent and the identity calculated from the set of loci were 0.011 and < 0.001, respectively. A deviation from the Hardy-Weinberg equilibrium was detected at all nine loci, i.e. significant heterozygote deficiencies, and several hypotheses accounting for this are discussed. The isolated loci carried independent information. Five polymorphic loci were amplified in a related sympatric species, L. (L.) scutellaris, which has relatively short genitalia. These microsatellite makers will be used to determine the paternity of offspring of females multiply mated in the laboratory and compare the selection pressures operating on genital length in these closely related species. and Yoko Matsumura, Izumi Yao.