Balanitis xerotica obliterans (BXO) is the most common cause of pathological phimosis in boys. Presented here is the case of a previously well 13-year-old boy who developed obstructive renal impairment (serum creatinine = 190 micromol/l) at least in part from phimosis due to BXO. A circumcision and, 2.5 months later, meatal dilatation were done. Nine months after his initial presentation, his serum creatinine returned to a permanently elevated nadir of 119 mumol/l. Presentation with the complications of phimosis can be delayed in teenage boys because they may feel embarrassed to come forward. Circumcision remains the definitive treatment of BXO induced phimosis though if the penile meatus is involved, more complex surgery is sometimes required. Topical steroids are useful for residual disease. Follow-up is very important due to the frequent involvement of the skin of the glans. In the very long term there is an increased chance of penile malignancy, which can occur even after circumcision.