We have undertaken the metrological assessment of the method for the quantitative determination of a number of non-steroidal anti-inflammatory drugs (NSAID) including ibuprofen, ketorolac, diclofenac, indomethacin, naproxen, and ketoprofen with the use of gas chromatography mass spectrometry in the model blood samples in the framework of the screening survey of medicinal and narcotic substances. The method was evaluated in terms of the following characteristics: specificity, linearity, correctness, precision (reproducibility), and intra-laboratory precision. The proposed method can be applied for the quantitative evaluation of indomethacin, ketoprofen, and naproxen content as well as for the preliminary quantitative determination of ibuprofen and diclofenac in the framework of the chemico-toxicological and forensic chemical analysis. The method can be employed for the quantitative determination of ketorolac from such characteristics as «linearity» and «reproducibility».