Post-transplant hypertension is a major risk factor for graft loss and patient survival; therefore, hypertension following renal transplantation must be treated strictly. There seems to be a strong association between hypertension, total body water (TBW) and dry weight. In this study, we report the relationship of body water and body composition with hypertension in post-renal transplant patients. Forty-five post-transplant patients were enrolled in the study. Blood pressure (BP) was labeled as controlled if BP was 120/80 mm Hg and not under good control if BP was above 120/80 mm Hg. Based on the number of antihypertensive medications a patient was taking, patients were divided into two groups: Group 1 patients on one antihypertensive drug and Group 2 patients on more than one antihypertensive drug. Nutritional status of the patients was assessed. Body composition (water compartments, body fat and lean mass) was assessed using bioelectrical impedance analysis (BIA). Patient data were compared with 30 healthy volunteers. In patients, systolic BP was associated with TBW (P = 0.016), extracellular water (ECW Lt; r = 0.99), ECW% (r = 0.78) and diastolic BP with TBW% (P = 0.003), dry weight (r = 0.76) ECW% (r = 0.95) and percent intracellular water (ICW%) (r = 0.79). Compared with controls, ECW and ECW% was higher in patients, and the ICW% was less in patients. There was significant difference in the actual weight of the patients and BIA-derived dry weight, although patients were clinically not edematous. The study showed a significant increase in diastolic BP with increase in dry weight. Significant difference in TBW was observed when the patients were grouped on the basis of the antihypertensive medication a patient was taking (one antihypertensive drug versus more than one antihypertensive drug). This study also showed an association between hypertension and overhydration. BIA may be a useful tool for the clinical assessment of overhydration in non-edematous patients.