Treatment of otherwise lethal ethylene glycol poisoning depends on rapid diagnosis, aggressive supportive care, appropriate use of alcohol dehydrogenase inhibitors and, in selected patients, hemodialysis. Next to that, specific measures to prevent renal or systemic calcium-oxalate deposition are important. We report the case of a 12-year-old girl who ingested more than five times the lethal dosis of ethylene glycol in a suicide attempt. At admission her serum ethylene glycol concentration was 88 mg/dl. Under treatment by ethanol infusions to block the alcohol dehydrogenase and by hemodialysis to eliminate ethylene glycol and its toxic metabolites, this level decreased to below 15 mg/dl within 36 h. The plasma oxalate level, however, rose to a maximum of 89 μmol/l (normal <6.3 ± 1.1) on day 3 and only normalized on day 7 after ingestion. In addition, urinary oxalate excretion was elevated (maximum 1.16 mmol/1.73m2/24 h). Both lead to calcium-oxalate oversaturation and hence to the risk of local (renal) or systemic crystal deposition. Therefore, alkaline citrate was given as a preventive measure to increase urinary oxalate solubility, but nephrocalcinosis still developed. Metabolic acidosis, hypocalcaemia, and neurological symptoms had not occurred. Four weeks after discharge, both plasma and urinary oxalate levels were normal.