From 1984 to 1989 we have examined endoscopically 191 patients who ingested, for different causes, some type of caustic substance. The mean age was 36.8 +/- 21 years. 57% were female and 43% males. The most common substance was lye (52%). The clinical symptoms consisted mainly of epigastric pain and odynophagia. The most prevalent lesion was oesophagitis, of variable degrees (58%). Complications related to the ingestion of the caustic appeared in 20% of the patients; three of them died. The most common sequela was oesophageal stenosis and secondly gastric stenosis. Males ingested acids more frequently than females (P less than 0.001). In 20% of the cases the ingestion of the caustic was for suicide while in children all the cases were accidents.