Patients with Inflammatory Bowel Disease (IBD) are exposed to nutritional risk. Malnutrition in Crohn's Disease (CD) and to a somewhat lesser in Ulcerative Colitis (UC) is very frequent. Depending on the severity of the disease, weight loss has been reported in 65% to 76% of those with CD and in 18% to 62% of those with UC. The role of Total Parenteral Nutrition (TPN) is essential in very severe cases where enteral nutrition is not tolerated or standard drug therapy is not effective. Nutritional therapy is important for the correction of nutritional deficiency, especially in cases where elective surgical treatment is required. This study examined the effects of preoperative TPN administration in patients with IBD. Since 1990, 29 pts, 13 (44.8%) male and 16 (55.2%) female with severe IBD; 16 (55.2%) with UC and 13 (44.8%) with CD were treated with TPN in our department in the preoperative period. Evaluation of this group was compared with a group which was not treated with TPN preoperatively: 61 pts, 34 (55.7%) male, 27 (44.3%) female; 50 (82%) with CD, 11 (18%) with UC. Evaluation of this group was compared with the group of patients who were subjected to surgical procedure without prior TPN administration, in total a number of 61, of whom 34 (55.7%) were male and 27 (44.3%) female patients. In this group, the number of patients with CD and UC was 50 (82%) and 11(18%) respectively. During the course of the study, the following parameters were examined: Body mass index (BMI), Disease Activity Index (CDAI/AI), laboratory parameters and the number of hospital days. The parameters were analysed before the surgical intervention, and one week and six months after the surgical intervention. The duration of the application of TPN was 12.5 +/- 5 days. The analysis of these parameters has shown that there is no statistically significant difference in the number of hospital days in both groups, which was 18.9 +/- 8.9 in the intervention group and 18.9 +/- 6.5 days in the control group, p = 0.9808, but analysis of the Disease Activity (CDAI/AI) has shown that patients who were on TPN were in a more severe stage of the disease. In the TPN treated group of patients none, 0 pts (0%), of the pts had no Index of Activity, 1.7 pts (24.1%) had Index 2 and 22 (75.9%) had Index 3. In the other group 3 pts (4.9%) had Index 1; 39 pts (63.9%) had Index 2 and 19 pts (31.2%) had Index of Activity 3. During the monitoring period of six months the activity of the disease was lower in patients treated with TPN. The BMI in the group of patients treated with TPN was lower in both sexes. It was lower than 18.4 in 7 males and 5 females; between 18.4 and 19.9 in 2 males and 4 females; between 19.9 and 25 in 3 males and 6 females; between 25 and 19.9 in 1 male and 1 female; there were no pts with BMI higher than 29.9. In the control non-TPN group, 5 males and 3 females had BMI < or = 18.4; 2 males and 5 females had between 18.4 and 19.9; 23 males and 13 females had between 19.9 and 25; 3 males and 5 females had between 25 and 29.9 and 1 male and 1 female had BMI higher than 29.9. The BMI had an increasing trend in the postoperative period in both groups. The laboratory parameters that we examined were: number of erythrocytes and sedimentation, number of leukocytes, haemoglobin levels, total number of lymphocytes, albumin level, C-reactive protein, orosomucoid, electrolytes; sodium, potassium, calcium and serum iron, the enzymes (AP, AST and ALT); level of bilirubin and urea and creatinine. The results were analysed using the Tukey honest significant difference test (HSD), ANOVA and Student t-test. Statistically significant differences were observed between preoperative and postoperative period in both groups. The intergroup comparison showed significant differences in the level of albumin, AST, ALT and bilirubin.