Gender identification in bird is important for both conservation program and forensic investigation. Since many bird species exhibit sexual monomorphism, this could lead to fraudulent cases in related communities. PCRbased techniques are the current standards for avian gender identification. Most assays target the specific introns of the chromo-helicase DNA binding gene (CHD) on sex chromosomes, which generate different fragment sizes on agarose gel electrophoresis. In this study, we validated four primer sets previously reported for avian sex determination (P2/P8, CHD1F/CHD1R, 2550F/2718R, and 1237L/1272H) using 1405 samples from 70 avian species commonly found in Thailand. The result showed that all four primer sets can be used for gender investigation of these avian species. However, the most efficient primer set vary depending on the species being investigated. Primer sets providing 100% identification accuracy for each bird species are reported.