We evaluated the performance of the Roche OnTrak Testcup-er (TC-er), an on-site drug-testing device, for the detection of amphetamines (AMP), barbiturates (BRB), benzodiazepines (BNZ), benzoylecgonine (BE), and opiates (OPI) in urine specimens from hospital emergency departments. This device utilizes a competitive binding microparticle immunoassay to simultaneously determine the presence of the following drugs or drug classes in urine at and above the following cut-off concentrations: AMP, 1000 ng/mL; BRB, 200 ng/mL; BNZ 200 ng/mL; BE, 300 ng/mL; and OPI, 300 ng/mL. One hundred forty-nine urine specimens received from emergency departments were simultaneously tested by the EMIT II monoclonal immunoassay (Emit) and TC-er. Specimens yielding discordant results were analyzed by gas chromatography-mass spectrometry. There was a 98% (146/149) agreement of results between the methods for the presence or absence of drugs. TC-er yielded 110 positive drug findings in 79 specimens, and Emit yielded 102 positive drug findings in 76 specimens. There was a 97% agreement between the methods for positive findings of at least one drug. The majority of discordant results were due to variations in selectivity of the assays for phenobarbital and BNZ metabolites. TC-er yielded a single false-positive result for amphetamines, and barbiturates, possibly three false-positive benzodiazepine results, and a single false-negative opiate finding. This represented four certain errors out of 745 total results, or a 0.4% error rate. If the three false-positive BNZ results were also considered, the error rate would be 0.9%. TC-er demonstrated acceptable linearity around the cut-off concentration of each drug. The TC-er was determined to be a reliable device for rapid on-site testing of emergency department urine specimens.