Castration is often used in male sheep to prevent losses in meat palatability, improve subcutaneous adipose tissue and prevent undesirable pregnancies. But, there is insufficient research on how long for the changes in biochemical profile to take place and finally stabilize as well as which parameters are definitely altered after castration in adult rams. To elucidate this issue, this research was carried on using 31 White Dorper males at 36 mo of age, when biochemical changes are not expected, since they reached adulthood. Animals were surgically castrated, with removal of the scrotum apex, under tranquilization, local anesthesia and using sterile materials. Antibiotic and analgesia treatments were performed for 3 d. Blood samples for measurement of urea, creatinine, albumin, total protein, GGT, AST, CK, HDL, LDL, VLDL, cholesterol, β-hydroxybutyrate (BHB), NEFA and triglycerides, were collected days before castration (D0) and, after that, on d 1, 3, 7, 15, 30, 60 and 9 mo. Castration had no influence on GGT, creatinine, total protein and cholesterol. Up until 15 d after castration, the others parameters were altered because of stress and surgery. Urea increased (P < 0.0001) from 19,85 (D0) to 32,43mg/dL (9 mo). Albumin decreased after surgery, possibly due to exudation, and returned to the same values as D0 on D60. AST increased after surgery, then decreased gradually and returned to normal on D15. CK decreased (P < 0.0001) from 230,1 to 103,4 U/L, which can be explained for the tranquil temper of rams after surgery, with the absence of fights, that used to be common. The HDL, BHB and NEFA decreased on D3 and remained low. Triglycerides and VLDL decreased on D1 until D15, then raised on D30 to the same values as before castration. The LDL values only increased on D1and on D3 they were similar to D0. The results showed that surgical castration, even under ideal surgical conditions, causes important changes in biochemical profile, especially in the first 15 d after surgery, with stabilization of values in 30 d. The castration alters the behavior of rams, decreases HDL, BHB and NEFA values and raises urea amounts.