The oral cavity is a unique site it has hard and soft tissues in close approximation. It has the vital functions like respiration, speech, mastication and digestion. It is a chief entry point for many pathogenic microorganisms in the body. The oral cavity might well be thought as porthole to the body because oral manifestations escort with many systemic diseases. In majority of the cases, oral involvement precedes the appearance of other symptoms or lesions at other locations. These oral manifestations must be properly predicted if the patient has to receive proper diagnosis and referral for treatment. A dentist  or oral physician thus can regularly be exposed to such conditions and play a key role in the diagnostic process of various systemic diseases. Apt knowledge of these oral manifestations is essential for early diagnosis, treatment and referral of cases. This paper is proposed as a general overview of conditions that have oral manifestations but also involve other organ systems.