The aim of this study was to compare the progression of renal grafts following treatment of an acute rejection event based on the histological diagnosis of a graft biopsy compared to a presumptive (clinical and laboratory) diagnosis. A historical cohort was used to study 44 patients undergoing a living haploidentical related donor renal transplant, using a similar immunosuppressive treatment: cyclosporine, azathioprine, and prednisone. Acute rejection events were treated with methylprednisolone (250 mg for 3 to 5 days) based on a histological diagnosis (biopsy group = 14) or on a clinical and laboratory diagnosis (presumptive group = 30), which consisted of an elevation over 20% in plasma creatinine in 24 hours and renal ultrasound or scintigraphy findings. The study demonstrated no significant difference in renal function (plasma creatinine) and other outcomes 2 years following transplantation in both groups. The results show that treatment of acute rejection based on a presumptive diagnosis is not a risk factor for unfavorable outcomes following 2 years of renal transplantation monitoring.