Posterior urethral valves (PUV) are the most common cause of lower urinary tract obstruction in male infants. They are the foremost cause of obstructive uropathy leading to renal failure in childhood. PUV represent a spectrum of severity from disease incompatible with survival to that which is minimal and quiescent until later life. The treatment of PUV remains a clinical challenge, requiring active management from infancy into adulthood to avoid progressive dysfunction and deterioration of both the upper and lower urinary tracts. While the primary pathology is obstruction caused by valves in the posterior urethra, the secondary pathology in terms of vesical, renal and sexual dysfunction adds to the long-term morbidity in this disease. Prenatal ultrasound has probably ensured that every child with posterior urethral valves will be diagnosed before birth.