Background:Patients undergoing radiation therapy for oral squamous cell carcinoma (OSCC) have an increased risk of developing oral candidiasis. Radiation-induced hyposalivation is thought to be a major predisposing factor for it. Radiation therapy for 2–3 weeks leads to increase in the number of candidal species in the oral cavity, eventually leading to oral candidiasis.Objective:To evaluate and correlate the prevalence of candidal species in the oral cavity of OSCC patients and to compare with radiation dosage at 3rd and 6th week following radiotherapy.Materials and Methods:This study includes fifty patients undergoing radiation therapy for OSCC. Patients were examined at 3rd and 6th week following radiation therapy, and smear samples were obtained from lesional sites and the radiation dose was recorded. Smear samples were cultured on CHROMagar, and identification of various candidal species was done on the basis of colony color and their morphology.Results:The present study isolated four types of candidal species, namely, Candida albicans, Candida glabrata, Candida tropicalis and Candida krusei. All the organisms, except C. krusei, showed a significant increase from 3rd to 6th week of radiotherapy whereas C. glabrata and C. tropicalis showed a sudden exponential increase. Total radiation dosage did not show any correlation to candidal colonization at 3rd and 6th week following radiotherapy.Conclusion:OSCC patients undergoing radiotherapy show an increase in candidal colonization which is independent of radiation dosage and may be related to other factors. However, such findings should be further evaluated using a larger sample size.