The present study was aimed to investigate the effect of flock age, air pressure during incubation period and litter types on blood plasma constituents of broiler chicks. A total number of 600 one day old hatching chicks (ROSS 308) were taken randomly nearly a similar in live body weight were used in this study. Chicks were randomly divided into equal 12 groups in a 2×2×3 factorial arrangement experiment according to flock age (younger breeder flock 33 WKS and older breeder flock 43 WKS), air pressure (normal 100719 and high, 1011000 Pascal) and three litter types (wood shaving, plastic and sand). The results obtained showed that, broiler chicks produced from younger breeder flock recorded significantly (p