Fifty isolates of Mycobacterium tuberculosis complex were tested for susceptibility to pyrazinamide (PZA) by the ESP (Trek Diagnostic Systems, Westlake, Ohio) and BACTEC (BD Biosciences, Sparks, Md.) test systems. Initial results showed concordance for 48 of the isolates. On retest, the two discordant isolates were resolved in favor of the ESP system. The ESP Myco susceptibility test system generates rapid, reliable PZA test results.