The data show differences in the relative sensitivity of ELISA in detecting diazepam exposure in different tissue types. Detection sensitivity was greatest in the bone marrow, followed by epiphyseal bone and diaphyseal bone, which suggests a heterogenous distribution in these tissues and a decreasing sensitivity with increasing dose-death interval. Further research is needed that involves the examination of the effects of longer dose-death intervals on the sensitivity of drug detection, including other drugs of forensic relevance with different chemical and pharmacological properties. Fifteen rats were given diazepam acutely (20 mg/kg, i.p.), and they were killed at various times after the administration of the dose. Marrow, epiphysis, and diaphyseal bone were isolated from extracted femora. Bone was cleaned, ground, and incubated in methanol. Marrow underwent ultrasonic homogenization. Extracts and homogenates were diluted in phosphate buffer, followed by solid-phase extraction and ELISA. Relative sensitivity of detection was examined in terms of relative decrease in absorbance (ELISA) and binary classification sensitivity (ELISA and LLC/MS/MS). 1 table, 3 figures, and 10 references