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Retinol or vitamin A is an essential fat-soluble vitamin. Because of the particular role of vitamin A in different tissues and organs, various clinical signs are seen during its deficiency. In addition, in cases of marginal deficiency without clinical signs performance defects, such as infertility are seen. This study was conducted to determine the serumic amounts of beta-carotene and vitamin A of sheep in Khalkhal city. During the summer of 2018; 200 blood samples (100 males and 100 females) were collected from jugular veins of sheep. Spectrophotometry was used for determination of vitamin A and β-carotene levels. The mean±SEM concentration of β-carotene and vitamin A of serum in the open breeding system were 19/5±9/3 (µg/dl) and 57/6±13/1 (µg/dl) respectively, and also in the closed breeding system these values were 19/2±9/6 (µg/dl) and 26/9±7/9 (µg/dl) respectively. The difference between vitamin A in the two groups was significant (p < /em>=0.000), but beta-carotene was not. There was no significant difference in levels of vitamin A and beta-carotene of serum in the four age groups and between the two sexes. In conclusion, the role of age, sex and nutrition in the serumic amounts of these compounds is significantly varied and laboratory results should be interpreted more cautiously.