Acute arsenic toxicity is rare, and there have been no pediatric cases of acute arsenic poisoning in the recent literature. We report a pediatric case of acute arsenic ingestion treated initially with British antilewisite (BAL) and D-penicillamine (DP), and later with dimercaptosuccinic acid (DMSA). A 22-month-old girl ingested 1 oz 2.27% sodium arsenate and developed immediate vomiting and diarrhea. The patient presented to a community emergency department with the following vital signs: blood pressure 96/72 mm Hg, pulse 160 beats/min, respirations 22 breaths/min. She was pale and lethargic. Gastric lavage was performed, and abdominal X-ray was normal. She continued to have gastrointestinal symptoms and received 3 mg/kg BAL. Sinus tachycardia persisted, with heart rate increasing to 200 beats/min. In 12 hours, she was asymptomatic and was started on oral DP. On day 1, 24-hour urine arsenic was 4,880 micrograms/L. She remained asymptomatic and was discharged on day 6 on oral DP. She did well except for a rash that could have been a side effect of DP. On day 8, when the day 5 24-hour urine arsenic level was returned at 650 micrograms/L, the patient was readmitted and started on DMSA. After 4 days on DMSA, the 24-hour urine arsenic level was 96 micrograms/L. White blood cell count and renal and hepatic function remained normal. The excretion half-life was approximately 2.5 days, which is at least 2 to 3 times faster than the spontaneous excretion half-life expected in adults. Long-term follow-up was unavailable.(ABSTRACT TRUNCATED AT 250 WORDS)