Cancer patients frequently experience malnutrition. Cancer and cancer therapy effects nutritional status through alterations in the metabolic system and reduction in food intake. In the present study, fifty seven cancer patients were selected as subjects from the oncology ward of Cachar Cancer Hospital and Research Centre, Silchar, India. Evaluation of nutritional status of cancer patients during treatment was carried out by scored Patient-Generated Subjective Global Assessment (PG-SGA). The findings of PG SGA showed that 15.8% (9) were well nourished, 31.6% (18) were moderately or suspected of being malnourished and 52.6% (30) were severely malnourished. The prevalence of malnutrition was highest in lip/oral (33.33%) cancer patients. The study showed that the prevalence of malnutrition (84.2%) was high in cancer patients during treatment.