A study of 1943 potentially toxic ingestions occurring in children under 6 years of age was conducted by 3 geographically and demographically diverse poison centres to determine the incidence of exposures to poison. Of the total group, 30.1% indicated that the child had experienced a prior poison exposure (12.0% in children under 1 year of age, and 41.3% of children between the ages of 3 and 5 years). Most repeaters (68.9%) experienced only 1 prior ingestion (range 1 to 15). Two prior ingestions were reported in 17.6% of repeaters; 3 prior ingestions in 4.4%. A profound effect of age on type of substance ingested was observed, with drugs accounting for 11.0% of ingestions in children under the age of 1 year, 23.2% in 1-year-old, and 49.9% in 2- to 5-year-old. A corresponding age-related decline in ingestions of household and personal care products was also noted. Although less marked than the age effect, a statistically significant propensity to re-ingest similar types of poisons was observed. Among repeaters, those with a prior ingestion of a drug subsequently ingested another drug 1.49 times more frequently than expected. A similar trend was observed with products (1.24 times more frequently) and plants (2.00 times more frequently).