In this prospectively collected data base multifactorial study, the influence of the peri-operative recipients' parameters on the transplanted kidney function were examined. One hundred and twenty-one patients who underwent first cadaver kidney transplantation in our unit were involved and were followed up for another 2 yr. The recipients were divided into three groups. Group I, patients with non-functioning grafts, group II, with delayed graft function, and group III, with good graft function. All routinely measured parameters were involved in the examination. The pre-operative haematocrit level differed significantly among the three groups. Significant intra-operative differences were found among the three groups in mean arterial pressure, (group I: 81 +/- 31 mmHg, group II: 90 +/- 24 mmHg, vs. group III: 108 +/- 26 mmHg, p < 0.01) at 5 min before revascularisation. The patients who had better post-operative kidney function, had lower pre-operative haematocrit level, and higher blood pressure in the different phase of operation, than those who had post-operative kidney function problems. The second warm ischaemic time in Group III was significantly shorter than in group I. (Group I: 51.5 min vs. group II: 47 min, vs. group III: 46.3 min, p < 0.001). Rejection rate was higher during the first 5 post-operative days in patients with non-functioning grafts. (Group I: 53% and group II: 24% vs. group III: 12% p < 0.001). The other examined parameters had not differed significantly among the three groups. The kidney function differences observed in the early (first 5 d) post-operative period, remained similar at the end of the next 2 yr. According to our results the peri-operative fluid-balance is one of the most important factors which may influence the success of the kidney transplantation.