Travel-related poisoning is an emerging social and public health emergency in Bangladesh but its cause and significance have not been determined. To investigate this syndrome we performed a prospective clinical study and retrospective analysis of hospital records in a general medicine unit of a public tertiary care teaching hospital in Dhaka, Bangladesh, using toxicological analysis by fluorescence polarization immunoassay (FPIA) and liquid chromatography coupled to time-of-flight mass spectrometry (LC-TOF MS). The participants of the prospective study were 130 consecutive patients aged 16-80 years who were admitted with central nervous system depression (Glasgow Coma Score 3-14) after using public transportation, in the absence of other abnormalities, from January through June 2004, and a convenience sample of 15 such patients admitted during 3 days in May 2006. In 2004-2006, travel-related poisoning increased from 6.1 to 9.5% of all admissions (210-309 of 3266-3843 per year), representing 46.6-55.7% of all admitted poisoning cases. Incidents were associated with bus (76%), taxi, train, and air travel, or local markets; 98% of patients remembered buying or accepting food or drinks before losing consciousness. Direct financial damage (missing property) was diverse and frequently existential. Among 94 urine samples analyzed by FPIA, 74% tested positive for benzodiazepines. Among 15 urine samples analyzed by LC-TOF MS, lorazepam was detected in all; five also contained diazepam or metabolites; nitrazepam was present in three. FPIA results obtained for these 15 samples were below the recommended cut-off in eight (53%; lorazepam only). Our findings show that the massive medicosocial emergency of travel-related poisoning in Bangladesh is the result of drug-facilitated organized crime and that benzodiazepine drugs are used to commit these crimes, suggesting modifications to the local emergency management of the victims of this type of poisoning. They also highlight the need for more research in the neglected field of acute poisoning in Bangladesh, and for criminal investigations of the use of benzodiazepine drugs in this country.