Gamma Glutamyl Transferase (GGT) is an enzyme responsible for the transportation of amino acids across the cell membranes, and for the metabolism of glutathione. The level of this enzyme in serum has been shown to be related in most cases to the presence of cancer in certain locations of the body. The concentration of some trace elements in serum has also been shown to be related to cancer. Blood samples from two groups, control & patients were prepared and quantitative determination of GGT & Se, Zn, Cu & Fe were carried out using standard procedures. It is found that the GGT- Serum level in patients is significantly higher than its level in control group. As for the trace elements studied, Cu-concentration was higher in CA-patients, while Zn, Fe & Se concentrations have shown a remarkable decrease in those patients when compared to the control group. Conclusions and suggestions for further studies were drawn and included in the thesis.