In this study, the effects of Cynarin, a plant extract ingredient, supplementation on bone structure and some blood parameters and the role of the form of feed on this effect was examined. Four hundred eight one day old hatched broiler chicks (Ross 308) were used in the research. The research was repeated 6 times with 4 equal groups having 120 animals each group. The diets of animals were prepared individually for each group as prestarter, starter, and grower period. There were 4 treatment arranged factorially with 2 feed form (mash and pellet) and 2 cynarin doses (none, 0.25g/kg). These groups were; mash form (D1), pellet form (D2), mash form+Cynarin (0.25g/kg feed) (D3), and pellet form+Cynarin (D4). The duration of the trials was 42 days. In this study, tibia weight, ash rate, tibia Ca and P concentration and some blood parameters were evaluated. The average tibia weight of the groups differed depending on the form of the feed (P<0.05), however it was observed that tibia ash ratio and bone mineral content have not changed depending on the diets. On day 21 it was determined that interaction between feed form and cynarin effected on serum urea values (P<0.05). Serum triglyceride value decreased (P<0.001) depending on the Cynarin supplementation in the diets and the form of the feed had an important role in this effect (P<0.03). On day 42, there were no effects of applications on selected serum parameters. Cynarin supplementation decreased serum phosphor (iP) (P<0.0001) and calcium (Ca) (P<0.006) values on day 21 and the form of the feed was also found important in this changes (P<0.002). During the same period, serum Alkaline phosphatase values also differed depending on the form of the diet (P<0.036). On day 42, negative effect of cynarin supplementation on iP concentration continued (P<0.0001). In conclusion, it was determined that cynarin supplementation decreased serum triglyceride concentration, however, the form of feed was more effective on the bone structure.