Cases involving acute fatalities due to ingestion of organophosphorus pesticides (OPs), such as chlorpyrifos, diazinon, malathion and parathion, are presented. Solid-phase extraction (SPE) and gas chromatography/mass spectrometry (GC/MS) were used for the analysis of OPs in postmortem blood. After extraction with an Oasis HLB cartridge, the eluent was evaporated to dryness under a nitrogen stream at 35 degrees C, reconstituted with ethanol, and then analyzed by GC/MS. Terbufos was used as an internal standard. Verification procedures, such as the limit of detection, limit of quantification, linearity of the calibration, precision and recovery were performed. Validation data were adequate for analyzing OPs in blood. Chlorpyrifos, diazinon, malathion and parathion were detected in 31 postmortem blood samples. Parathion was the most frequently detected compound among the four pesticides. The mean concentrations of chlorpyrifos, diazinon, malathion and parathion were 0.72, 1.03, 0.82 and 2.90 mg/L, respectively.