Fetal intestinal perforation causes a sterile inflammatory reaction of the peritoneum called meconium peritonitis. Twelve patients studied in the perinatal period serve to describe the classical fetal and neonatal signs and symptoms, the iconographical findings, treatment and prognosis. All but one infant, with a meconium pseudocyst, presented with the fibro-adhesive variety. Two were caused by cystic fibrosis, two by organic obstruction, one by fetal appendicitis and another two by ischemic necrosis of part of the ileum. In one of the latter two, the probable mechanism was feto-fetal embolisation following the in utero death of a co-twin. One idiopathic perforation, diagnosed in a preterm infant, healed spontaneously. The neonatal mortality rate was 18%. Primary enteric anastomosis was feasible in 3, Bishop-Koop anastomosis in 2 and an intestinal stoma in two others. Apart from the two survivors with cystic fibrosis, seven have no late gastro-intestinal sequelae.