Background: Candida represents the most common cause of invasive fungal disease, and candidal blood stream infections (CBSI) are prevalent in the ICU. Inappropriate antifungal therapy (IAT) is known to increase a patient's risk for death. We hypothesized that in an ICU cohort it would also adversely affect resource utilization.Methods: We retrospectively identified all patients with candidemia on or before hospital day 14 and requiring an ICU stay at Barnes-Jewish Hospital between 2004 and 2007. Hospital length of stay following culture-proven onset of CBSI (post-CBSI HLOS) was primary and hospital costs secondary endpoints. IAT was defined as treatment delay of ≥24 hours from candidemia onset or inadequate dose of antifungal agent active against the pathogen. We developed generalized linear models (GLM) to assess independent impact of inappropriate therapy on LOS and costs.Results: Ninety patients met inclusion criteria. IAT was frequent (88.9%). In the IAT group antifungal delay ≥24 hours occurred in 95.0% and inappropriate dosage in 26.3%. Unadjusted hospital mortality was greater among IAT (28.8%) than non-IAT (0%) patients, p = 0.059. Both crude post-CBSI HLOS (18.4 ± 17.0 vs. 10.7 ± 9.4, p = 0.062) and total costs ($66,584 ± $49,120 vs. $33,526 ± $27,244, p = 0.006) were higher in IAT than in non-IAT. In GLMs adjusting for confounders IAT-attributable excess post-CBSI HLOS was 7.7 days (95% CI 0.6-13.5) and attributable total costs were $13,398 (95% CI $1,060-$26,736).Conclusions: IAT of CBSI, such as delays and incorrect dosing, occurs commonly. In addition to its adverse impact on clinical outcomes, IAT results in substantial prolongation of hospital LOS and increase in hospital costs. Efforts to enhance rates of appropriate therapy for candidemia may improve resource use.