Renal transplantation (RTx) is the treatment-of-choice for a significant number of patients with end-stage renal disease. Despite recent accomplishments, both surgical and medical complications still exist. Urinary tract infection (UTI) is the most common infectious complication after RTx, while asymptomatic bacteriuria is the most common manifestation of bacteriuria. UTI can impair graft function, potentially reducing graft and patient survival.The aetiology changes with time after RTx. The epidemiology of most of these infections is also changing with resistant organisms being isolated more often than in the past. Several factors increase the risk of infection in RTx patients, and the presence of multiple risk factors in the same patient is not uncommon. These include immunosuppression, urinary flow impairment (most often caused by stenosis or strictures at the vesicoureteral junction, benign prostate hypertrophy or vesicoureteral reflux), and treatment-related factors such as the use of catheters and double-J stents. Early diagnosis and effective treatment are key elements in salvaging both the allograft and the patient. This chapter reviews the definitions, epidemiology, microbiology, screening, clinical manifestations, diagnosis, impact on renal allograft function, evaluation after diagnosis, treatment, prevention including long-term prophylaxis, and the unique challenges of diagnosing and managing recurrent bacterial UTIs in a RTx care setting.