The antihypertensive drug therapy and the peri-operative plasma potassium trend in end stage renal disease (ESRD) patients undergoing renal transplant were analysed. Out of consecutive 107 live related donor renal transplant, complete data available for 74 patients between June 1991 and March 1993, were entered in proforma and analysed. On the basis of antihypertensive or no antihypertensive drugs prescribed, patients were grouped in 6 categories. Group I patients taking no antihypertensives were taken as control. All patients were comparable for their age, sex, weight, immunosuppressive therapy, anaesthetic and fluid management during surgery. At the time of induction of anaesthesia, patients taking atenolol (plasma K+ levels being 5.34 +/- 0.75 mmol/l in group II and 5.44 +/- 0.63 mmol/l in group III) or captopril (serum K+ level being 5.05 +/- 0.94 mmol/l in group V) in combination with nifedipine and with or without clonidine had significant hyperkalaemia than the patient without antihypertensives (serum K+ level being 4.49 +/- 0.71 mmol/l). Patients, on these two antihypertensives, frequently needed active treatment of alarming hyperkalaemia (blood K+ more than 5 mmol/l and tall 'T' wave in lead II) and cardiac arrhythmias. In conclusion, ESRD patients taking atenolol or captopril are needed to be frequently monitored for blood potassium levels and it would be advisable to avoid these drugs to control hypertension in ESRD patients, especially, when scheduled for renal transplantation.