Female birds possess one Z and one W chromosome, whereas male birds possess two identical Z chromosomes. Thus, the presence of a W genetic marker is diagnostic of the female sex. Capillary electrophoresis with buffer containing an entangled solution of hydroxyethylcellulose was used to separate the polymerase chain reaction (PCR) amplified bird sexing genes CHD-Z and CHD-W. The relative standard deviations (RSD) were less than 0.6% for the male genes and less than 0.4% for the female genes for six runs and detection limits of 0.1 ng/mu L were obtained with laser-induced fluorescence (LIF) detection. Using a DNA ladder and theoretical models for DNA separation in sieving media, the sizes of the two bird genes were determined.