The aim of our study is to know the effect of adding cyproheptidine as a feed additive (growth promoter) to the broiler diet. Sixty birds (Ross breed) one day old were been grouped randomly into two groups: a treatment group and a control group, and the chicks were housing and feeding for 49 days (from 1/11 – 19/12/2022). and measure some serum biochemical parameter and growth performance. The result showed significantly affected (p<0.05) by the treatment group throughout the production period (1-49) days, an increase in body weight, Live body weight gain, Food intake, and weight of abdominal fat, heart, and leg, all other carcass parameters. The serum content of creatinine tends to drop (0.91 mg/dl) while the urea content tends to increase (1.30 mg/dl) in the treatment group. Cyprohptadine was significantly affected (p<0.05) on the serum protein content in the treatment group (2.12 g/dl) than the control group (2.84 g/dl) and there was no significant effect of cyproheptadine in serum contents of (ALAT) and (ASAT), decreased serum content of Cholesterol compared than the control group. From these results, Cyproheptadine is an effective and well-tolerated appetite stimulant in the broiler. So, it can be used to increase the weight of broilers in a shorter period of time than usual.