Clean intermittent catheterization (CIC) has replaced urinary diversion as the treatment of choice for patients with neurogenic bladder. Yet, no well controlled studies are available assessing the efficacy of CIC over ileal loop diversion (ILD). Consequently, a one-year pospective study was carried out comparing short-term patient morbidity, infection rates, and bacterial organisms in 33 children with meningomyelocele. Twenty-four of the children were treated with CIC whereas nine children had an ILD. A minimum of four cultures per year were obtained on each patient. Patients maintained on CIC had 36.8% of their cultures positive for bacteriuria whereas children with ILD had 61.8% of their cultures positive (P less than .001). The incidence of bacteriuria associated with clinical signs and symptoms was similar in both groups. Four of 24 children treated with CIC had sterile urine whereas none of the children with ILD were persistently free from bacteriuria. Only five of 24 children receiving CIC had 50% or more of their cultures positive as contrasted with seven of nine children with an ILD (P less than .01). Escherichia coli accounted for approximately one third of organisms recovered from infected urine in both groups. Although the short-term morbidity associated with both treatment modalities is similar, the incidence of asymptomatic bacteriuria in children maintained on CIC is significantly less than in children with ILD. Whether this factor plays a role in determining long-term morbidity is a subject for further study.