Over a seven year period 23 neonates with spontaneous pneumothorax and/or pneumomediastinum (SPP) were diagnosed in 24,739 live birth infants (0.09 percent). Of these, eight (35 percent) had renal anomalies. Three showed severe renal dysfunction and typical Potter facies and died within 34 hours. Their lungs were shown to be hypoplastic with a reduced lung weight: body weight ratio or a low radial alveolar count. One patient had left hypoplastic and right polycystic kidneys. Four patients with obstructive uropathies did not show the typical facies, and SPP was the only sign leading to their early diagnosis and therapy. We conclude that nephrologic evaluation is indicated in newborns with unexplained SPP and recommend abdominal ultrasound and if indicated renal scan and/or intravenous pyelography as part of the initial evaluation.