The presence of therapeutic drugs in postmortem human scalp hair was investigated. Hair samples from 21 cadavers known to have taken antidepressant and antipsychotic drugs were solubilized in 1 M sodium hydroxide. Drugs were extracted using solvent extraction procedures and analyzed by gas chromatography-mass spectrometry (GC-MS) and high performance liquid chromatography (HPLC). Antidepressant drugs detected were amitriptyline, dothiepin, doxepin, imipramine, trimipramine, and mianserin. Antipsychotic drugs detected were haloperidol, chlorpromazine and thioridazine. Concentrations of these drugs and their metabolites ranged from 1.3 to 242 ng/mg hair. Segmental analysis demonstrated that the drug concentrations detected were either consistent with the known dosing regime of the deceased, or were able to provide an indication of drug use within the last few months prior to death. This study reinforces the potential of hair as a useful tissue in forensic investigations, in establishing a history of past exposures to therapeutic drugs.