
Background and Objective: The objective of the study was to identify the predominant oral microbes associated with oral squamous cell carcinoma in their pre and post radiotherapeutic status. Materials and Methods: A total no of 40 patients were selected, having squamous cell carcinoma and not receiving any treatment. Swabs are collected from the ulcerated area and microbiological evaluation was performed. Swabs were again collected from the same patient receiving radiotherapy as treatment modality just one month ago. The microbes were identified by gram stain and biochemical test. Results: The results suggested both aerobic and anaerobic bacteria were colonized over the surface of the ulcer, but the distinguishing feature between these two groups that after radiotherapy the % of bacterial count (especially the anaerobes) markedly diminished. Conclusion: It was concluded from the results that, the diseased individuals suffering from Oral Squamous Cell Carcinoma in their pre-radiotherapeutic status showed the presence of Streptococcus, Staphylococcus, Pseudomonas, Proteus, Klebsiella and Bacillus subtilis, Actinomycetes, Fusobacterium in higher concentration, whereas in post radiotherapy phase more or less the same group of microbes were found, but in a significantly reduced amount. This was because of the fact- the removal of the tumour mass as well as effect of radiotherapy.