Venous blood samples were collected monthly from 60 male and 60 female Sinclair(S-1) miniature swine from 1 through 36 months of age. Hematologic parameters evaluated included: erythrocyte count, packed cell volume, hemoglobin concentration, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, leukocyte count and differential leukocyte counts. Mean erythrocyte count increased from 3 through 9 months of age and declined thereafter. Mean packed cell volume and hemoglobin concentration decreased from 1 to 3 months of age, increased from 3 through 10 months of age and remained stable thereafter. From 7 through 36 months of age, females had greater mean packed cell volume and hemoglobin concentration than did males. Mean corpuscular volume and mean corpuscular hemoglobin increased linearly from 3 through 24 months of age and remained stable thereafter with females having greater mean corpuscular volumes and mean corpuscular hemoglobins than did males. Mean corpuscular hemoglobin concentration increased linearly from 1 through 30 months of age. Mean leukocyte count decreased from 1 through 9 months of age and remained stable thereafter. From 10 through 36 months of age, mean leukocyte count was greater for males than for females. From 6 through 24 months of age, mean per cent lymphocytes was greater for females than for males; whereas, mean per cent neutrophils was greater for males than for females.