The relationship between absence or presence of grossly visible lesions in the cheeks, lips, and oropharynx (C.L.O. burns) and the incidence, site, and degree of visceral burns was evaluated in all children referred to our hospital for a suspected caustic ingestion during a 10-year period. All children underwent eso-gastro-duodenoscopy within 24 hours. Of the 156 children, 96 (61.6%) showed no visible signs of contact with the caustic substance; however, in 36/96 (37.5%), endoscopy revealed burns in one or more visceral sites. Eight of 36 children (22.2%) sustained potentially dangerous lesions (second to third degree). Sixty of 156 children (38.4%) showed visible lesions; in 30/60 (50%), endoscopy revealed other burns in one or more visceral sites. Fourteen of 30 patients (46.6%) sustained potentially dangerous lesions (second to third degree). A total of 50 esophageal burns have been recorded: first degree (E1), 32; second degree (E2), 12; third degree (E3), 6. Two of 12 patients with E2 lesions and 6/6 with E3 lesions developed esophageal stenosis. One patient in this latter group died because of complications related to a tracheostomy. A total of 31 gastric burns have been recorded: G1 (22), G2 (6), G3 (3). One gastric perforation was observed in the G3 group, whereas the remaining two lesions healed with residual asymptomatic scarring. Minimal scarring was observed in two of six patients with G2 burns. A total of eight lesions have been recorded in the larynx [L1 (3), L3 (1)] and in the duodenum [D1 (2), D2 (2)].(ABSTRACT TRUNCATED AT 250 WORDS)