A prospective review of 51 cases of tobacco ingestion and 5 cases of nicotine resin chewing gum exposure was conducted to evaluate the incidence and degree of toxicity caused by these products in children. A dose-response relationship was observed for cigarette exposures. Nine of 10 children ingesting more than one cigarette or three cigarette butts developed signs or symptoms, while 12 of 24 ingesting lesser amounts became symptomatic (P less than 0.01). Severe symptoms (e.g. limb jerking and unresponsiveness) were only seen with the larger amounts. Nicotine resin gum produced toxicity in 4 of 5 children who chewed 1/2 to 4 pieces. Agitation, lethargy, tachycardia, hypotension, abdominal pain, and vomiting were seen within 30 min of exposure to the gum.