Abstract : Algeria's main sheep production areas are the steppic zones, where the Algerian sheep has acquired aptitudes that characterize its particular productive performance. In recent years, this breed has suffered a regression in numbers and spatial occupation. The causes of which appear to be numerous. In the present study, the aim is to evaluate the impact of season and sex on certain blood parameters in lambs and ewe lambs in a semi-arid zone. This research was carried out on 42 heads of lambs and ewe lambs, aged 4 months, in the north-east of semi-arid areas. Algeria. Glucose, cholesterol, triglycerides, urea, creatinine concentrations and some haematological parameters (RBC, HB, WBC, PLQ) were determined. Statistical analysis of the results revealed no significant seasonal influence on glucose, creatinine or triglyceride levels, with the exception of an increase in triglyceride levels in spring compared with winter in both sexes. Winter cholesterol levels were relatively higher than spring levels in lambs and ewe lambs. However, a difference between spring and winter cholesterol levels was observed in males and females. Cholesterol levels obtained in winter remained relatively higher compared to values obtained in spring in lambs and ewe lambs. Analysis of (WBC,RBC,Hb) levels over the two seasons revealed no significant difference, whereas platelet levels showed a significant reduction in lambs during the winter. To assess the effect of sex, statistical analysis revealed no effect on the biochemical parameters studied, whereas this effect appeared significantly on white blood cell levels and a very significant increase in red blood cell and platelet levels.