Fatal ingestion of methotrimeprazine is unusual, and while therapeutic drug levels are established as concentrations between 0.02 to 0.14 mg/L, fatal levels are not. The following describes a case of fatal suicidal ingestion of methotrimeprazine in which the measured concentration of methotrimeprazine in the blood was 4.1 mg/L. In addition, the major metabolites of methotrimeprazine, desmethylmethotrimeprazine, and methotrimeprazine sulfoxide were also measured at 2.0 and 1.8 mg/L, respectively. Methotrimeprazine and its metabolites were also measured in urine, bile, and vitreous humor. These results are compared with other case reports of methotrimeprazine fatalities reported in the literature.