The expression levels of cytochrome P450s were examined in different camel tissues by western blotting and semi-quantitative polymerase chain reaction. Camelus dromedarius liver microsomes were found to express different P450s isoenzymes constitutively. The maximum expression of P450 protein was seen in the camel liver in the order of P450 2E1, 1A1, 3A and 2B1/2. Camel extrahepatic tissues, kidney, spleen and the lung showed detectable levels of P450s 1A1 but lower than that noticed in liver. Detectable level of P450 2B1/2 was also observed in camel lung (29.5 vs. 58% liver microsomes). P450scc and 21-hydroxylase were found to be differentially expressed only in camel testis. Partial sequences of these P450s genes showed high similarities with the human P450s. These results demonstrate that the multiple forms of P450s are differentially expressed in camel tissues and that the relative levels of expression are comparable with other mammals. These observations might be important in understanding the differential susceptibility of camel tissues to the toxic effects of xenobiotics and environmental pollution.