The structure of the quail spleen at late embryonic stages and during the post-hatching period was determined by light microscopy using different staining techniques. Whereas the spleen growth was limited compared to the body growth in embryonic stages. the relative spleen weight increased 2.8 fold during the first 4 weeks post-hatching in quail. At 10 days of egg incubation, erythropoiesis was predominant. but on the 11(th) day. granulocyte islets were formed around vessels and the ellipsoids appeared around the penicilliform capillary on the 12(th) day. The capsule of Schweigger-Seidel sheath (CSSS) wrapped them on the 15(th) day and although they were not well defined, the pen-arterial lymphatic sheath (PALS) and the peri-ellipsoidal white pulp (PWP) appeared on the 16(th) day. At hatching, the granulocyte islets disappeared and the white pulp was gradually colonized with lymphocytes according to the age. In parallel, the thickness of the CSSS increased, especially after the 10(th) day post-hatching. In 30 day old quails. the PALS mainly consisted of small lymphocytes. The number of lymphocytes was superior in the PALS areas than in the PWP in 60 days old quails. Plasma cells were found in the PWP and especially in the red pulp around pulp veins during the post-hatching period. In conclusion, the quail spleen undergoes structural changes throughout the pre- and post-hatching periods.