In the present clinical evaluation of Triage immunoassay for detection of drugs of abuse, we examined a possible connection between the laboratory skills of the personnel using it and the quality of analytical results; we also evaluated the degree of concordance between the Triage results and those obtained by an instrumented fluorescence polarization immunoassay (FPIA). Three groups of evaluators with different laboratory skills and two sets of urine samples from subjects with different rates of drug consumption prevalence were included in the study. Urines were analyzed by the Triage analytical device at the collection site. A second analysis was performed in a toxicology laboratory, and the results were compared with those obtained by FPIA. Nonconcordant results were confirmed by gas chromatography-mass spectrometry and HPLC. Results were independent of the laboratory skills of the evaluators. The agreement for each drug calculated for two populations with differences in prevalence of drug consumption was almost the same, except for benzodiazepines. No differences between Triage and FPIA results were observed for samples clearly over or under cutoff concentrations. Globally, the Triage device, in a clinical situation, demonstrated performance comparable with that of an instrument-based immunoassay and, in some cases (e.g., for benzodiazepines), the Triage performance was even better.