The HPLC-integrated liquid-solid extraction (LSE) has several advantages for the initial "clean-up" of biological samples as compared to conventional methods, e.g., the repeated direct injection of untreated biofluids, such as quantitative removal of the protein matrix, improved precision, accuracy, sensitivity, etc. Since these aspects are particularly important in the direct stereoselective methods, the review summarizes recent trends and relevant applications in HPLC and CE, including sampling issues, instrumentation and validation alternatives, and potential limitations concerning pharmacokinetic and toxicokinetic studies.