A continuing social problem is presented by the large number of individuals who use crack cocaine. Recent research has identified unique pyrolysis products of crack or burned cocaine as anhydroecgonine methylester (AEME) and ecgonidine (ECD) through gas chromatography/mass spectrometry (GC/MS) that allow for the detection of crack use distinct from other cocaine use. However, there have been no large-scale studies to document the presence and prevalence of these substances in sweat. A new sweat-testing appliance called a fastpatch was developed for this study. Through mild heating and a slightly larger collection pad than a standard Pharmchek( trade mark ) sweat patch, this product shows the promise of shorter required wear periods than standard sweat patches, and possibly longer time-periods of detected use. One hundred and eighty subjects wore 360 fastpatch prototypes (one per hand). However, subsequent analysis determined that only one patch per subject was needed to obtain sufficient sweat eluate for GC/MS. Cocaine use was detected in sweat of 92% of subjects through GC/MS, comparing favorably with 91% with EMIT urinalysis. Crack metabolites were detected in 54% of subjects. The predominant analyte detected was AEME. There were no significant differences in detection rates between 15-, 20- and 30-minute wear periods. All wear periods detected both cocaine use in general and crack use successfully. These results suggest that crack use as distinct from other cocaine use can be detected in sweat and that fastpatches are a promising new way to detect drugs of abuse.