Purpose. The impact of a rapid peptide nucleic acid fluorescence in situ hybridization (PNA FISH) assay with an antimicrobial stewardship intervention on the treatment of Candida infections was studied. Methods. The utility of implementing the PNA FISH assay with an antimicrobial stewardship intervention in hospitalized patients with candidemia was evaluated by measuring the median time to Candida species identification, time to targeted therapy, and clinical outcomes, including time to culture clearance, hospital length of stay, and hospital mortality. Secondary objectives included determining the cost-effectiveness of the PNA FISH assay by assessing estimated antifungal drug costs (as average wholesale price) before (June 26, 2009-September 19, 2010) and after (September 20, 2010-June 13, 2011) test implementation and confirming test accuracy. For both groups, laboratory personnel notified the physician of the results of Gram's stain from blood culture. Results. Time to targeted therapy significantly decreased after the implementation of the PNA FISH assay (p = 0.0016). The postimplementation group had a higher rate of culture clearance (p = 0.01). Median time to species identification was 0.2 day with the PNA FISH test versus 4 days with routine methods (p < 0.001). Accounting for the cost of the test itself and the cases in which patients were switched to more-expensive therapy on the basis of the test, we estimated that the PNA FISH test resulted in savings of approximately $415 per patient. Conclusion. Implementing a PNA FISH test to identify Candida species from yeast-positive blood cultures in conjunction with a pharmacy-driven antimicrobial stewardship protocol decreased the time to targeted antifungal therapy and the time to culture clearance. Copyright © 2012, American Society of Health-System Pharmacists, Inc. All rights reserved.