Lymphoma is the most common hematopoietic tumor in dogs and manifests as a proliferation of malignant lymphoid cells primarily affecting the lymph nodes or solid visceral organs. We describe the use of capillary gel electrophoresis (CGE) with a laser-induced fluorescence (LIF) detector based on polymerase chain reaction (PCR) to rapidly detect a disorder of the canine T-cell receptor gamma (TCRgamma) gene. After the PCR amplification of the specific TCR( gene in dogs, the 90-bp DNA fragment amplified was separated in a fused-silica capillary by CGE-LIF. Under an electric field of 375 V/cm and with a sieving matrix of 1.5% poly (ethyleneoxide) (M(r) 600,000), the amplified PCR products were analyzed within 4 min by CGE separation. When the CGE-LIF method was applied to real clinical samples of the specific DNA fragment of the TCR( gene, the migration time and the corrected peak area showed relative standard deviations (n=5) of 0.29% and 0.58%, respectively. Both methods of CGE-LIF and slab gel electrophoresis showed same results for nine clinical samples. This PCR/CGE-LIF technique may prove to be a new fast and simple tool for the rapid diagnosis of the PCR-amplified DNA of canine T-cell lymphoma.