CONTEXT Ulcerative colitis is an inflammatory bowel disease involving superficial inflammation of the mucosa of the colon, rectum, and anus, sometimes including the terminal ileum. When in clinical activity, the disease is characterized by various daily evacuations containing blood, mucus and/or pus alternating periods of remission. OBJECTIVE To compare nutritional parameters (dietary, biochemical and anthropometric) among patients with ulcerative colitis followed up on an outpatient basis over a period of 1 year and during periods of intestinal inflammatory activity and remission. METHODS Sixty-five patients were studied over a period of 1 year and divided into two groups: group 1 with inflammatory disease activity (n = 24), and group 2 without disease activity (n = 41). Anthropometric measures, biochemical parameters, quantitative food intake, and qualitative food frequency were analyzed. RESULTS A significant reduction in body mass index and weight and in the intake of energy, proteins, lipids, calcium, iron and phosphorus was observed in the group with inflammatory activity (group 1) when compared to the period of clinical remission. The most affected food groups were cereals, legumes, oils, and fats. In contrast, in group 2 significant differences in triceps and sub scapular skin fold thickness, total protein, hemoglobin and hematocrit were observed between the first and final visit. Calcium and vitamin B6 intake, as well as the consumption of legumes, meat and eggs, and sugar and sweets, was significantly higher than on the first visit. CONCLUSION Patients with ulcerative colitis followed up on an outpatient basis tend to be well nourished. However, the nutritional aspects studied tend to worsen during the period of inflammatory disease activity.