The purpose was to determine if blood cocaine or metabolite concentrations would accurately reflect the severity of clinical findings in patients presenting to the emergency department, identifying those requiring therapeutic intervention or those at risk for poor outcome. Blood for determination of cocaine and metabolite concentrations was drawn from patients and were determined by an extractive alkylation/mass spectrometry procedure. The mean blood concentrations (mg/L) in 111 patients were as follows: cocaine, 0.26 +/- 0.5; ecgonine 0.42 +/- 0.47; ecgonine methyl ester 0.21 +/- 0.37, norcocaine 0.03 +/- 0.17; benzoylecgonine 1.28 +/- 1.29, cocaethylene 0.02 +/- 0.06. Two patients died, 23 required hospital admission, and 88 were discharged from the ED. There was no statistical correlation between cocaine or any metabolite concentration and the severity of clinical symptoms, disposition, need for treatment or outcome. Blood cocaine and metabolite concentrations should be interpreted with caution because they vary widely and do not predict the severity of clinical findings, the incidence of adverse effects, outcome, or need for interventional therapy.