Background The mortality and morbidity associated with oral squamous cell carcinoma (OSCC) can be greatly reduced if tumor markers which can detect OSCC at an early stage are available. The use of saliva as an alternative to blood could provide a substantial advantage in sampling convenience. Cancer antigen 125 (CA 125) is a tumor-associated antigen found to be increased in epithelial tumors like oral, breast and ovarian cancers. Aim To determine whether salivary CA 125 levels are increased significantly in OSCC patients than the control group. Materials and methods Sixty OSCC patients and 60 healthy controls were taken for the study. Saliva samples from both the groups were collected, centrifuged and supernatant fluid were subjected to ELISA for assessment of CA 125. The mean salivary CA 125 values of OSCC patients and control group were statistically analyzed using Mann-Whitney U-test. Results The mean salivary CA 125 concentration of OSCC group was 320.25 and that of control group was 33.14. Thus, CA 125 was found to be significantly increased in the saliva of OSCC patients than the control group (p < 0.001). Also, there was significant increase in the CA 125 levels as the stage of OSCC increased. Conclusion The convenience, reliability and noninvasive nature of salivary CA 125 testing makes it a feasible adjunctive diagnostic tool for detection of OSCC. How to cite this article Balan JJ, Rao RS, Premalatha BR, Patil S. Analysis of Tumor Marker CA 125 in Saliva of Normal and Oral Squamous Cell Carcinoma Patients: A Comparative Study. J Contemp Dent Pract 2012;13(5):671-675.