Background: Gastrointestinal (GI) cancers are responsible for more deaths from cancer than any other cancers. These patients are at risk for disease-related malnutrition which has been linked to an increase in post operative complications. Despite research, guidelines for preoperative nutritional assessment are lacking. The study was aimed to assess the nutritional status of patients in gastrointestinal malignancy, impact of nutritional supplementation and its impact on outcome of surgery.Methods: This cross-sectional study was conducted on patients of gastrointestinal malignancy attending Dept. of Surgery, Dr. D.Y. Patil Medical College, and Hospital, Pimpri, Pune. Institute Ethics Committee clearance was obtained before starting the study. 45 newly diagnosed patients of gastrointestinal malignancy were included in the study after informed consent.Results: At the start of this study 26.66% were well nourished, 35.55% moderately nourished, and 37.77% poorly nourished. At 6 weeks after supplementation 60 % were well nourished, 24.4 % moderately nourished, and 7 % poorly nourished. Surgical site infection (SSI) occurred in 7 patients of which 57.14% were poorly nourished, 28.57 % were moderately nourished. Anastomotic leak occurred in 3 patients of which 66.66% patients were poorly nourished. Average number of days of hospital stay for well nourished patients was 6.23 and for poorly nourished patients 14.14.Conclusions: Malnutrition is a concern in gastrointestinal malignancies. Delay in surgery upto 6 weeks is permissible to enhance patients’ nutritional status. Proper nutritional supplementation significantly improves nutritional status. Complications like SSI and anastomotic leak; hospital stay are significantly reduced after improvement in nutritional status.