Post transplant erythrocytosis (PTE) is a condition of pathologically increased hemoglobin (Hg) and hematocrit (Hct) concentration occurring after renal transplantation. The aim of our study was to evaluate the impact of graft function on post transplant erythrocytosis. All patients who got transplanted between September 98 and July 2002 at our center in whom Hg was found to be greater than 16 on three consecutive clinic visits were retrospectively reviewed. PTE developed in 51 (13%) of 381 patients. There were 40 males and 11 females. The mean age of the patients was 29.9± 7.9 years. The time of diagnosis of PTE was 7.8± 6.3 months. Serum creatinine at the time of diagnosis of PTE was 1.4± 0.7 mg/dl. PTE developed after a mean duration of 7.8 ± 6.3 months. Hypertension defined as elevated systolic BP above 140 mm Hg was present in 28 (54.9%) patients. Twenty nine patients received ACE inhibitor (Enalapril) with significant decline in Hg from16.5± 0.3mg/dl pre enalapril to 13.0± 2.3 mg/dl after 3 months of treatment (p=0.0001). In thirteen of them enalapril was withdrawn without significant rebound erythrocytosis at three months. Serum creatinine in the withdrawl group was higher (1.9± 1.4 mg/dl) at this time compared with those who continued enalapril (1.4±0.6). Nine patients who were not treated with enalapril did not show any significant change in Hg at three months. Discontinuation of enalapril does not cause rebound erythrocytosis if good graft function is not maintained.