Abstract: The changes in glucose, cholesterol and Triglyceride (TG) levels were investigated during reproductive process stages of rainbow trout (Onchorhynchus mykiss). TG level decreased significantly from maturation to spawning in both sexes. Cholesterol levels fluctuated significantly during reproduction period. Glucose levels increased at maturation then decreased throughout the spawning. Low density level value increased to ovulation then fluctuated to post-spawning. High density lipoprotein values sharply decreased then increased and fluctuated significantly during the reproduction. Very low density lipoprotein values immediately increased then decreased and fluctuated significantly from pre-maturation to post spawning.