The aim of this study is to determine the effects of adding different levels of red pepper oil to quail diets on performance, slaughtering characteristics, and some serum parameters. For this purpose, a total of 300-day-old and mixed-sex quail chicks were randomly assigned to 5 treatment groups with 6 replications of 12 chicks each. Experimental animals were fed for 35 days with 5 different diets prepared by adding 0, 300, 600, 900 or 1200 mg/kg red pepper oil. During the experiment, quails were given ad-libitum feed and water. According to the results of the experiment, the effect of adding red pepper oil to the diet on the performance, carcass traits and visceral weights of the quails was statistically insignificant. Triglyceride and TAS concentrations of serum were significantly affected by the addition of red pepper oil to the diet. The highest triglyceride and TAS levels in the group with 300 mg/kg red pepper oil added; however, the lowest triglyceride and TAS levels were obtained in the groups supplemented with 600 mg/kg and 1200 mg/kg red pepper oil, respectively. According to this study findings, it can be said that the addition of red pepper oil to the diet in growing quails has a positive effect on serum triglyceride and TAS values when used between 300 mg/kg and 600 mg/kg in the diet, without adverse effects on performance and carcass characteristics.