ABSTRACTObjective: To study the clinico-microbiological profile of oral candidiasis in head and neck squamous cell cancer (HNSCC) patients undergoingcurative radiotherapy (cRT).Methods: Patients undergoing cRT and developing oral candidiasis were enrolled. Clinical features such as pain and xerostomia were recorded.Candida isolates from lesions were speciated using CHROMagar (Himedia Inc.), and antifungal susceptibility was determined using microbrothdilution (MBD). Patients were followed up to study the clinical course of infection.Results: Of the 100 patients undergoing cRT, 79 developed oral candidiasis. Median duration to development of infection was 4 weeks (range:1-6.5 weeks). Mucositis was observed in 76 (96.2%) and xerostomia in 53 (67.1%) patients; 61 patients (77.2%) had symptoms attributable tocandidiasis. However, there was no correlation between severity of infection and mucositis (p=0.84) or xerostomia (p=0.51). Candida albicans was themost frequent (47 patients, 59.4%) isolate, followed by Candida tropicalis (23 patients; 29.1%). All isolates were sensitive to nystatin, but fluconazoleresistance/dose-dependent susceptibility was noted in 26 (32.9%) isolates. Both Candida krusei and two of four Candida glabrata isolate exhibitedfluconazole resistance. All patients received treatment for Candidiasis. On follow-up, 1 month after cRT, oral candidiasis resolved with gradualrecovery of mucositis in all patients.Conclusion: Candida albicans was the most common cause of oral Candidiasis in HNSCC cRT, and all isolates were susceptible to nystatin in-vitro.All lesions resolved with recovery from mucositis. In addition, as no patient developed systemic candidiasis, it appears that oral candidiasis thoughtroublesome is curable with treatment.Keywords: Radiation mucositis, CHROMagar, Microbroth dilution, Antifungal susceptibility.