Hypertension is a serious complication in children after renal transplantation, it is an important risk factor not only for graft loss but also for cardiovascular morbidity and mortality of transplanted patients. The etiology of posttransplant hypertension is multifactorial - pretransplant hypertension, damaged native kidneys, immunosuppressive therapy (steroids, cyclosporine, tacrolimus), renal graft artery stenosis and chronic allograft nephropathy are the most common causes. Ambulatory blood pressure monitoring (ABPM) is the best method for blood pressure (BP) evaluation in children after renal transplantation, it often discloses especially night-time hypertension. The prevalence of posttransplant hypertension ranges between 60-90% depending on the method of BP measurement and definition of hypertension. Left ventricular hypertrophy (LVH) is a frequent end-organ damage in hypertensive children after renal transplantation occurring in 50-80% of them. All classes of antihypertensive drugs are used in the treatment of posttransplant hypertension, it has never been proven that one class would be better than another in BP lowering effects or in slowing the progressive loss of graft function associated with chronic allograft nephropathy. Control of hypertension in transplanted children is poor - only 20-50% of treated children have normal BP. The reason for this poor BP control seems to be an inadequate antihypertensive therapy rather than a true resistance of posttransplant hypertension. The unsatisfactorily low control of hypertension can be improved by increasing the number of antihypertensive drugs, especially of angiotensin converting enzyme inhibitors and diuretics. Reduction or elimination of steroids, cyclosporine or tacrolimus is able to reduce BP in transplanted children, however, it could be associated with a risk of acute rejection. Nephrectomy of the diseased native kidneys also decreases BP in transplanted patients but it is performed very rarely in children. There is still a great potential for improvement of antihypertensive treatment that could result in improvement of both graft as well as patient survival in children after renal transplantation.