Squamous cell carcinoma of oral cavity is of malignant tumors, which causes cancerous complications. DNA damage, mainly because of products of oxidative stress like reactive oxygen species, is a frequent mutagenic that triggers carcinoma. Smoking increases the probability of cancer incidence. Saliva is the first biological medium to interact with external compounds, especially smoking substances. The present study overviews the salivary level of some remarkable compounds in relation with smoking and squamous cell carcinoma.To collect data, English literature was searched in databases including PubMed, ScienceDirect and Google Scholar. The keywords used for search were as follows: ‘Carcinoma, Squamous Cell’, ‘Smoking’, ‘Saliva’, and ‘Biomarkers‘. The inclusion criteria were the presence of salivary chemical factors in relation with oral cancer and influence by smoking. Out of 239 found articles, only 56 were selected.Our results demonstrated the potential role of salivary biochemistry to predict and/or treat complications with cancer in both smoker and non-smoker individuals.Changes in concentrations of salivary chemicals including antioxidants, total antioxidant, glutathione and uric acid, epithelial growth factor, cytokine biomarkers, superoxide dismutase activity, and transcriptome were related to squamous cell carcinoma and could be used as potential biomarkers for cancer prognosis; moreover, enhancement of antioxidant level might be a potential treatment.