The material lying within the crypts of 11 human palatine tonsils was studied by scanning and transmission electron microscopy. There was a mixture of desquamated epithelial cells and various non‐epithelial cells, mainly lymphocytes, with some mononuclear pahgocytes and plasma cells, and a few erythrocytes, neutrophil leucocytes and mast cells. Many of the cells were degenerating and there was a great deal of cellular debris. The non‐epithelial cells seemed to have entered the crypts from the lining epithelium, probably by being caught up between superficial squamous epithelial cells as they sloughed into the lumen. The widespread cellular degeneration in the crypts suggested that the cells were being lost from the body and that they had no further immunological or phagocytic function. This also suggested that the first level of defence mechanisms of the tonsil was in the epithelium, not in the crypt lu