Transplantation of kidneys (TK) is the best way of curing patients with terminal kidney disease. Unfortunately, right after the operation, different kinds of complications are possible and might happen to transplant. The worst and the most often complication is acute rejection (AR). The aim of work is to find the most often clinical signs and symptoms of AR. The aim of research is to value the influence of AO on function of graft and to find the influence of AR on surviving patients and graft. This study has been done on 91 patients, 62 male and 29 female patients in the age of 38.58 +/- 11.4. Patient are divide in two groups: experimental group which includes 29 patients that have had one or more episodes of acute rejection. We used serum concentration of creatinine defined by Cocroft-Gault curve to measure function of transplant. Time of patients and graft survival is estimated by Caplan-Meier curve. In a group of patients with acute rejection we registered 42 episodes of dysfunction of graft which are treated as AR. The average creatinine in a group of patients with acute rejection was 183.42 +/- 65.39 micromol/L. Clearance of creatinine of group patient without AR is much bigger (p < 0.0001) than average clearance of creatinine of patients with acute rejection. Average serum creatinine in this group of patients is 147.59 +/- 62.57 and it is quite smaller (p < 0.002) than average creatinine at patients with acute rejection. Survival of all patients after five years is 91%, survival of patients without acute rejection is 96%, and with acute rejection is 80% (p < 0.014). Five year survival of graft is 78%, at the patients without acute rejection is 96% and at the patients with acute rejection is 64% (p < 0.0001), which is quite shorter. Clinical image of acute rejection is unspecific. There is not arranged values of serum creatinine although in some research those values are 130-170 micromol/L. This values includes patients which did not have an acute rejection. Five year survival patients and graft in our patients that did not have an acute rejection is same as in the results of relevant centers. But survival of patients and grafts in patients that had an acute rejection is little bit lower than it is in the results in relevant centers. There is no clinical picture than can help you to recognize an acute rejection because many other dysfuncion look the same. Acute rejection reduces function of transplant. Survival of patients and graft is mutch longer in the patients without acute rejection.