Because PG is generally believed to have low toxicity, it was introduced in the 1930s as a replacement solvent for the more toxic ethylene glycol (EG). PG is widely used for diverse purposes. Its industrial uses are related to its heat exchange properties, making it useful in antifreeze and as a synthetic lubricant in hydraulic fluids. This paper reports on two cases of suicide and one case in which the manner of death was undetermined. In all of the cases, PG was detected in postmortem toxicologic analysis. In one case, PG was the vehicle for self-administration of a euthanasia preparation, and death was due to a combination of drugs in which PG was a minor component. In the second case, PG was the only agent detected; and in the third case, PG was detected along with EG. In the latter two cases, PG or a mixture of PG and EG resulted in hyperosmolar metabolic acidosis. Previous studies have suggested that PG toxicity is unlikely to occur in healthy adults without renal disease unless massive amounts are ingested. Although PG has low toxicity, it must be included in the differential diagnosis of patients with metabolic acidosis. In rare cases, such as one examined in the current study, it may be the sole cause of death; or as in the other two cases, it may act in concert with other chemical agents to contribute to death. The absolute lethal blood concentration of PG has yet to be determined. 1 table and 19 references