Background: Age has been found to be one of the most important factors affecting kidney transplant outcome. In our study, we evaluated the impact of combined age of living donor and recipient on kidney transplant outcome. Methods: Retrospective cohort study conducted on 3068 kidney transplant recipients who underwent kidney transplantation at Mansoura Urology and Nephrology Centre between March 1976 and December 2019, divided into four groups according to recipient and donor age, group I: Kidney transplant recipients < 40 years from donors < 40 years (1665 kidney transplant recipients), group II: Kidney transplant recipients < 40 years from donors ≥ 40 years (932 kidney transplant recipients), group III: Kidney transplant recipients ≥ 40 years from donors < 40 years (320 kidney transplant recipients) and group IV: Kidney transplant recipients ≥40 years from donors ≥ 40 years (151 kidney transplant recipients). Results: Incidence of acute rejection and chronic rejection was higher in group I and of lower incidence in group VI. Incidence of post-transplant hypertension, diabetes, hepatic impairment and malignancy was higher in group III and lower in group II with statistically significant difference (p value <0.05). Conclusion: Young donor to young recipient transplantation was associated with higher incidence of rejection. Old donor to young recipient transplantation was associated with the best patient survival, lower incidence of post-transplant medical complications but the worst graft survival. Young donor to old recipient transplantation was associated with higher incidence of post-transplant medical complications and malignancy and worst patient survival. Old donor to old recipient transplantation was associated with the lowest incidence of rejection and the best graft survival.