Smoking is a common practice and damages almost all organs and systems of the body. Oral cavity is often overlooked yet such an important region. Its rich flora contains many microorganisms that cause local and systemic diseases if microbiological flora is altered. Cigarette smoke renders oral mucosa epithelium to be susceptible for colonization of pathogens. These pathogens can cause or contribute formation of systemic diseases such as diabetes and obesity. Also smoking causes mutations that can lead to cancers. Many cancerous or precancerous lesions and bad breath attributed to smoking. This review focuses smoking related oral cavity conditions and their mechanisms.