Introduction: The expected values of hematologic and serum biochemical parameters in domestic animal species can be affected by breed, age, environment, and nutrition. Established breed-specific REFERENCE intervals (RI) are an important tool for monitoring the health of sheep. There is a lack of published data on biochemical RI for Sngsari sheep. Thus, the aims of this study were to establish RI for select of serum biochemical parameters for Sangsari sheep by REFERENCE Value Advisor (RVA) method and provide information on the studied parameters for both sex of this breed in order to form a basis for clinical interpretation. Materials and Methods: Sixty healthy Sangsari sheep including 26 ewes and 34 rams (2– 4 years old) were chosen from the breeding station of Sangsari sheep among 150 sheep in Damghan, Semnan, Iran. The type of feeding, all the animals had free access to water and to good-quality alfalfa hay (90. 0 % DM, 15. 8 CP % DM, 50. 4NDF%DM, 31. 6ADF%DM, 5. 8 lignin% DM, and 2. 2 EE % DM). Concentrate (23 % oats, 36 % corn, 38 % barley, and 3%mineral and vitamin supplements) was provided once daily (200 g per animal per day). In the sampling day, breeder signed a subscription form and completed a primary questionnaire consisting of specific questions about past and current health status, sexual status, medications used, and familial and reproductive medical history. Complete physical examinations were performed by the same experienced veterinarian on each sheep. In order to reduce stress, blood samples were taken in the station with minimal changes in the usual schedule of the sheep. Blood samples (taken from the jugular vein) were collected in simple tubes in order to separate the serum (centrifuged at 3000 rpm for 10 min) for biochemical analysis. Samples transported at +4 ° C to the laboratory department of the Faculty of Veterinary Medicine, Semnan, Iran. Biochemical parameters were measured by a autoanalyzer. These parameters included alkaline phosphatase (ALP), gamma glutamyletransferase (GGT), aspartate aminotransferase (AST), blood urea nitrogen (BUN), total protein (TP) and albumin (Alb). For statistical analysis, data were analyzed by REFERENCE Value Advisor and outliers were deleted if detected according to Tukey or Dixon. RIs, according to sample size, were determined using a robust method and following Box-Cox transformation of data. The data were normally distributed, and differences between sexes in biochemical parameters were analyzed using independent sample T test. A value of P<0. 05 was considered as significant. Results and Discussion: The RI of biochemical parameters obtained from adult healthy Sangsari sheep includes the following: ALP 49. 24-564. 84 u/l; GGT 24. 14-62. 23 u/l; AST 10. 86-338. 40 u/l; BUN 6. 91-26. 43 mg/dl; TP 5. 19-13. 95 gr/dl and Alb 0. 92-3. 63 gr/dl. Established RI of biochemical parameters for ewes and rams, respectively including: ALP 29. 98-702. 89 u/l; GGT 22. 41-54. 49 u/l; AST 1. 36-279. 89 u/l; BUN 5. 9526. 86 mg/dl; TP 5. 75-12. 83 gr/dl; Alb 0. 84-2. 77 gr/dl and ALP 106. 08-568. 55 u/l; GGT 20. 80-58. 30 u/l; AST 360. 12 u/l; BUN 8. 15-26. 04 mg/dl; TP 4. 66-15. 59 g/dl and Alb 0. 74-3. 77 g/dl. Interpretation of the biochemical results in different breeds of sheep, with regard to RI for each parameter, in conjunction with history, clinical findings and other paraclinical tests helps the clinician to reach a definitive diagnosis. A unique feature of Sangsari sheep is that they are highly adaptable with desert and mountain ranges with high tolerance of drought conditions. This breed is also relatively small size and light weight, and most studies have focused on genetic characteristics associated with this trait. In view of the characteristics mentioned above and considering the lack of REFERENCE range for biochemical parameters, it is necessary to determine REFERENCE intervals in Sangsari sheep. In order to establish a comprehensive REFERENCE interval in Sangsari sheep, a select biochemical parameters were evaluated in the present study. Almost most of the established RI for biochemical parameters in this study differed from previously published RI, so that the lower and upper limits of RI of theses parameters (with the exception of BUN) were lower and higher than the values previously reported. Differences between obtained RI for the Sangsari sheep and previously reported RI for other breeds may be attributed to variations in hormonal influences, hydration status, dietary differences, or adaptations to a desert environment, age, breed, season of study and analytic method. Conclusion: The obtained data provided REFERENCE interval for biochemical parameters in Sangsari sheep for the first time. Present study demonstrates significant differences in most of the biochemical parameters. REFERENCE intervals determined in this study provide a baseline for interpreting biochemical results in Sangsari sheep, and contribute to optimization of the management of this species.