The authors have developed and verified the precision and accuracy of new automated cloned enzyme donor immunoassays (CEDIA®) for haloperidol and bromperidol, and cross-validations have been performed with conventional semiautomated EIA kits (MARKIT®-M) and high-performance liquid chromatographic (HPLC) methods. The CEDIA® method provides a quick (about 10 minutes) assay for haloperidol or bromperidol, requiring no serum/plasma pretreatment or predilution. The CEDIA® haloperidol/bromperidol assay showed little or no cross reactivity with either their metabolites or many drugs commonly coprescribed. MARKIT®-M revealed considerable cross reactivity values proportional to the spiked amounts of reduced metabolites. Precision, accuracy, recovery, and linearity testing for the CEDIA® assay were all sufficient for clinical use. Significant linear correlations were found between CEDIA® and HPLC in measuring haloperidol (CEDIA® = 1.06 × HPLC + 0.869; n = 44, rs = 0.913, P < 0.001) and bromperidol (CEDIA® = 1.06 × HPLC + 0.606; n = 56, rs = 0.914, P < 0.001) concentrations. This study has, therefore, demonstrated that the CEDIA® assay has a quick run time with high precision and accuracy, and this method is a useful tool for the TDM of haloperidol or bromperidol.