Oral cavity functions as an early indicator for a variety of systemic diseases. Early and accurate diagnosis of these underlying systemic disorders entails thorough examination of the oral mucosa, gingiva, teeth, tongue and other oral tissues. Although gingival changes may be related to local factors in the oral cavity, it can also be an expression of systemic conditions such as blood dyscrasias, endocrinal imbalance, and nutritional deficiencies. Leukemia, a malignancy of white blood cells is a dreadful disease, which, if not diagnosed properly and treated early may result in significant morbidity and mortality. Oral changes may be the first and only presenting signs in leukemic patients. This paper aims to throw light on an interesting case of acute leukemia diagnosed on the basis of oral signs and emphasizes the importance of thorough oral examination to identify the threatening condition.