Objective: Fungal infections are a main reason for mortality of critically ill patients in Intensive Care Units (ICUs). Recently, fungal infections have been on rise. Lack of a specific marker for fungal infections has led to some problems in diagnosing these infections. Scant data exist on serum procalcitonin (PCT) levels in high‑risk patients with invasive fungal infections, such as ICU patients. Materials and Methods: In this prospective study conducted in 2014–2015 in Al‑Zahra Hospital, Isfahan, Iran, 64 people were investigated. The PCT levels of the patients were measured at 0, 24, 48, and 72 h as well as 7 and 14 days of the ICU stay. Moreover, a blood sample was taken from each person every 3 days and examined for positive BACTEC Candida fungal culture. Results: Nine (15%) patients had candidemia. The mean serum PCT level was not significantly different between the patients with and without candidemia at admission and 24, 48, and 72 h of the ICU stay (P > 0.05), but was significantly different on 7 and 14 days of the ICU stay (P < 0.001). Conclusion: This study demonstrated that the serum PCT levels increased significantly in the patients with candidemia hospitalized in ICUs. Therefore, serum PCT, as a marker, can be relied on, in addition to other symptoms and factors, for taking a decision about the initiation of treatment with antifungal drugs. Besides that, further studies with larger sample size are recommended to examine the predictive value of PCT for invasive fungal infections.