A modified capillary electrophoretic method for the determination of nitric oxide correlated nitrate in several tissue homogenates is described in this study. The method was developed using a running buffer consisting of 200 mM lithium chloride and 10 mM borate buffer at pH 8.5, in a fused-silica column total 82 cm, effective 43 cm length and 75 μm I.D. The signal was measured at 214 nm and controlled current of 200 μA (equivalent to 12.7 kV) was applied in the reversed polarity direction. The sample was injected by vacuum pressure 50 ms (25 nl). In these conditions, bromide as internal standard and nitrate appeared at 7.2 and 8.9 min, respectively. Whole validation procedures were applied and satisfactory results were obtained. The nitrate levels of the tissue homogenates of control and L-NAME applied (heart, brain, kidney, stomach, lung, testis and liver) were monitored by the present method and it was decided that the method is precise and accurate. © 2001 Elsevier Science B.V.