Gas chromatography-mass spectrometry (GC-MS) analysis of meconium specimens screening positive for cannabinoids by the EMIT 20 Assay showed a low confirmation rate for 11-nor-9-carboxy-delta 9-tetrahydrocannabinol (THCCOOH). A study was designed to investigate the possible contribution of other delta 9-tetrahydrocannabinol (THC) metabolites, including glucuronides, to the overall response of the EIA. delta 9-THC-glucuronide was synthesized in order to develop the most efficient procedure for hydrolysis of glucuronides in meconium. Procedures were developed for the extraction and GC-MS analysis of delta 9-THC, 11-OH-delta 9-THC, 8 alpha- and 8 beta-OH-delta 9-THC, 8 beta,11-diOH-delta 9-THC, and THCCOOH, after enzymatic hydrolysis of meconium extracts. It is concluded that enzymatic hydrolysis of meconium extracts is necessary for efficient recovery of delta 9-THC metabolites; delta 9-THC and its 8-OH metabolite(s) are basically absent in meconium specimens; and 11-OH-delta 9-THC and 8 beta,11-diOH-delta 9-THC contribute significantly to the immunoassay response of meconium extracts. Analysis of several meconium specimens that screened positive for cannabinoids but failed to confirm for THCCOOH showed significant amounts of 11-OH-delta 9-THC and 8 beta,11-diOH-delta 9-THC. Therefore, GC-MS confirmation of cannabinoids in meconium should include analysis for these two metabolites in addition to THCCOOH.