Six commercially available solid adsorbent materials were evaluated for their applicability as effective tools for extraction of drugs from aqueous and human plasma samples. Ten model compounds were selected as representative of the acidic, basic, amphoteric, hydrophobic, and hydrophilic drug classes. Percent recovery and precision data for each model drug on each solid adsorbent material were calculated using spiked water and/or plasma samples. Octadecylsilane materials were the best overall choice for extraction of the different chemical classes of drugs from water and plasma samples, giving both highest recovery and best reproducibility data for a majority of the drugs studied. It was also determined that good extractability for basic drugs could be obtained using either XAD-2, Clin-eht® or cyanopropyl columns. In addition, XAD-2 gave good recoveries of amphoteric compounds and Clin-elut® was good for hydrophobic drugs.