Hypomagnesaemia has been implicated as a contributor to the cyclosporine toxicity. Some patients treated with cyclosporine develop hypophosphatemia and hypo­calciuria. Methods: Serum magnesium level were measured in 157 (62 female and 95 male) renal transplant recipients for correlation with cyclosporine level. Patients were divided in two groups, a low mg and a normal mg group based on the mean mg level. Others blood chemistries in cluded serum Creatinine, calcium and phosphate. Hypomagnesaemia was detected in 10.2% recipient patient. The mean cyclosporine level were significantly higher in the hypomagnesaemia (510.28 ± 23) than normomagnesemia group (354, 87±181), (P=0.002). Mean age of hypomagnesaemia patients was 50.7±12.47 years and that of patients with normomagnesemia was 42.9±12.1 years (P=0.02). Neither assays correlated with serum calcium and phosphate ( P=0.6 and P=0.9 respectively). According to the results of this study there is significant correlation between cyclosporine and hypo magnesium. Therefore it is recommended that serum level of magnesium be monitored regularly in renal allograft recipients' receiving cyclosporine.