The effect of cinnamon powder (CNP) feeding on some blood metabolites in broiler chicks was studied in a 49-day experiment. The feeding program consisted of a starter diet until day 21, a grower diet until day 42 and a finisher diet until day 49. There were five treatments: a negative control diet, without the additive (control: T1); 250 mg/kg (T2); 500 mg/kg (T3); 1000 mg/kg (T4); and 2000 mg/kg (T5) of CNP in the diet. A total of 320 one-day-old mixed-sex broilers (Ross 308) were distributed into 16 pens with 20 chickens each, comprising 3 replicates per treatment (except for T1, which had 4 replicates). Serum glucose was measured weekly and reported periodically. At the end of the experiment serum cholesterol, triglycerides, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities were determined. There were no significant differences among treatments regarding broiler performance and carcass characteristics, except for the finisher phase, when T2 resulted in a significant decrease in feed conversion ratio and weight gain (p<0.05). In the lowest level of cinnamon supplementation (T2), a significant increase in glucose level in starter, finisher and overall rearing period was observed, as well as an increase in triglyceride levels at the finisher phase as compared to T4 and T5 (p<0/05). However, cholesterol, AST and ALT levels were not statistically different among treatments. Therefore, it was concluded that the use of cinnamon powder can affect on some blood metabolites and broiler performance