Abstract: One thousand and three hundred chicks were used to describe body weight, hematocrit percentage (HTC), hemoglobin concentration (Hb), total plasma protein (TP) and albumin concentration (Alb) of two recently characterized local Saudi chicken lines Hajar 1 and 2 over the first 30 weeks of age. Three hundred and twenty male plus three hundred and five females of Hajar 1 and three hundred and forty six males plus three hundred and twenty nine females of Hajar 2 lines were used. At hatch, initial body weights were recorded individually, then blood samples were collected and body weight were recorded individually at 2, 4, 6, 8, 10, 12, 14, 16,18, 22, 26 and 30 weeks of age. The results indicated the genetic group effect on the body weight in male birds starting from the second week of age. The genetic group also affected HTC after 12 weeks of age. The sex effect was observable at most of the evaluated parameters. The results showed the effect of line-sex interaction on TP and Alb at late stages of the experiment. The study provides the first set of results to describe some blood parameters for Hajar 1 and 2 chicken lines. The results emphasized the effect of genetic group and sex besides their interaction in different ages on the changes in the selected blood parameters. The results revealed partial explanation to support previous findings about production performance for those lines. The study highlighted the importance of assessment of locally characterized chicken lines to figure out their unique characters.