The objective of this study was processing reduced fat sausage by using one fat mimic like chitin at different levels (5, 7.5 and 10 %), reduced fat sausage without chitin (control) and high fat sausage (control). Chemical composition, physical and sensory properties of uncooked and cooked sausage treatments were evaluated. Also, biological and biochemical changes were examined in rats fed on high and reduced fat sausage treatments. Results indicated that, decreasing fat content in sausage treatments led to significant decrease of sensory properties. Meanwhile, addition of chitin with 5 and 7.5 % to reduced fat sausage treatments led to improve their sensory properties. Values of sensory properties decreased with increase in the level of chitin in the sausage. Generally the highest overall acceptability was recorded for high fat sausage control followed by reduced fat sausage prepared with 5 % chitin with nonsignificant differences between them. Also, decreasing fat content increased cooking loss due to the high water content of RF sausages besides decreasing water holding capacity and plasticity. On the other hand, addition of chitin with 5 and 7.5 % reduced cooking loss and increased each of water holding capacity, plasticity. Results of biological evaluation indicated that, rats fed on diet contained high fat sausage had the highest value of liver enzymes activity (GOT and GPT), triglycerides, total lipid, total cholesterol, LDL- cholesterol and VLDL-cholesterol beside being the lowest of the HDL- cholesterol value. Meanwhile, rats groups which fed on diets contained reduced fat sausage prepared with 5 and 7.5 % chitin had the lower values of previous parameters except being higher at of HDL- Cholesterol when compared with rats group fed on reduced fat sausage (control) without chitin addition.