A high-performance liquid chromatographic method with diode-array detection (HPLC/DAD) for systematic toxicological analysis of human blood or plasma samples is presented. After single-step liquid/liquid extraction at pH 9.5 using chloroform/2-propanol/n-heptane (60:14:26, v/v/v), the drugs elute isocratically from a NovaPak C18 (Waters) 4-micrometers column (300 mm x 3.9 mm, i.d.) at 30 degrees C, with methanol/tetrahydrofuran/pH 2.6 phosphate buffer (65:5:30, v/v/v) as the mobile phase (flow rate 0.8 mL/min). Full UV spectra from 200 to 400 nm (resolution 1.3 nm) are recorded on-line during the 20 min chromatographic run. Solute identification may be automatically performed by comparison of analytical data (retention times and UV spectra) with references of 311 pharmaceuticals, toxicants and drugs of abuse stored in a computerized library. The method is simple, rapid, relatively inexpensive and highly specific. The previously reported applications of HPLC/DAD technology to drug screening are reviewed, and the interests and limitations of the method are discussed in the light of this literature.