A total number of 47 one week age suckling Chios crosses lambs were assigned to two groups, a control group receiving no ascorbic acid supplement and the other received supplemental ascorbic acid (2 grams per animal every other day). At the age of 9 weeks ar imals were exposed to direct sunlight and direct sunlight with exercise with walking for one hour (4 km/h) under solar radiation. Some physiological and hematological parameters were measured. Lambs exposed to solar radiation and exercise showed highly significant P(0.01) increase in respiratory rate and temperatures of rectum, skin and wool. Ascorbic acid treated lambs had lower respiratory rate and rectal temperature than control lambs. Exposure to solar radiation and exercise decreased the concentrations of hemoglobin (Hb), packed cell volume (PCV) %, total count of RBC's and WBC's /mm blood, serum glucose and thyroxin (T4), while the concentrations of serum albumin, cholesterol and cortisol hormone were increased. Dietary ascorbic acid reduced the changes in PCV,% , Hb and serum total protein due to sun exposure and exercise. Dietary ascorbic acid increased serum T4 concentration and decreased serum cortisol hormone. These results means that dietary ascorbic acid could improve heat tolerance and blood profile in suckling lambs.