Five commonly used commercial am[4ietaimiies (AMs) and opiates (OPs) immunoassay test kits: HYCOR accuPINCH™, Drug Screening System (DSS) MACH TV® Screen™, Princeton BioMeditech (PBM) Biosign™ and International EKagnostic Systems LD. Block™ were evaluated for their cutoff verification and assay performance with standardized and confirmed urine specific ens. Cutoff verification was evaluated at several cutofTs for commercial AMs and OPs test kits. The assay performance was evaluated with authentic urine specimens confirmed by GC/MS. Results indicated that the real cutoffs for most AMs or OPs test kits were lower than those reported. accuPEINCH™, Abifiign™ and LD.Block™ were better than MACH IV® Screen™ and ONTRAK ™ for AMs test kits; accuPINCH™, AbuSign™, LD.Block™ and ONTRAK™ were better than MACH IV® Screen™ for OPs test kits.