Aim: This study aimed at studying the incidence of abdominal malignancies in the patients presenting as acute abdomen and the various presentations in which they present. Materials and Methods: The study was conducted in the Department of General Surgery, Lord Buddha Koshi Medical College and Hospital, Saharsa,Bihar, India for 18 months.required surgery for acute abdomen were taken for the study and the incidence of malignancy in these cases were statistically assessed. Results: Out of the 400 patients who were operated for non-traumatic acute abdomen 73 patients i.e. 18.25% were found to have intra-abdominal malignancy. Carcinoma colon was the commonest malignancy, 52.05%. Carcinoma stomach and rectum were the next most common malignancy. Commonest presentation was as a case of intestinal obstruction, 79.45% followed by perforation 23.28%. Conclusion: In the era were the incidence and early detection of abdominal malignancies are on a rise, a significant portion of these cases present with acute abdominal symptoms and the morbidity associated with such a presentation is of importance. Early detection of the disease by screening is the solution for this.