The spleen is a special organ that is crucial to the functioning of our circulatory and immunological systems. Also, the spleen removes abnormal red blood cells (RBCs) from circulation, helping to maintain the balance between red blood cells creation (erythropoiesis) and elimination. The aim of this study is to find out the difference in the thickness of the spleen capsule between the study groups. The collected specimens were divided into three groups like Group 1 (0 to 14 years), Group 2 (14 to 50 years), and Group 3 (over 50 years). Hematoxylin and eosin (HE) staining to diagnosis thickness of capsule. The results showed increased thickness of spleen capsule with advanced age; the thickness was; in G1, G2, and G3 (14.938± 1.07, 21.074±3.34, and 52.828±19.53) respectively. Conclusion, thickness of spleen capsule increased with aging.