The aim of this study was to evaluate urinary infection frequency in kidney transplanted patients. Infection frequency was assessed in 116 patients (81 males and 35 females; mean age 36.2 years) after renal transplantation. During four year follow-up 41% patients suffered one or more episodes of infection. Bacterial infection caused by Escherichia coli were most frequent. The control group consisted of healthy medical staff and the investigations showed significantly over frequency of infection.