Present evidence suggests that a majority of murine CD3⁺ intraepithelial intestinal lymphocytes (IEL) are extrathymically derived T cells and that these extrathymically derived IEL phenotypically express the CD8 homodimer (CD8αα). Recently, CD3⁻ IEL have been reported to express the recombination activating gene (RAG‐1), suggesting that precursors to extrathymically derived CD3⁺CD8⁺αα IEL exist on the intestinal epithelium. To study in detail whether these CD3⁻ IEL can develop into CD3⁺CD8⁺αα IEL, we analyzed the CD3⁻ IEL subset and found that it can be separated into two subsets, namely CD3⁻CD8⁻ and CD3⁻CD8⁺ IEL. We show that (1) CD3⁻CD8⁻ IEL are mostly small, non‐granular and phenotypically Pgp‐1⁺ IL‐2R⁺ B220⁻, while CD3⁻CD8⁺ IEL are mostly large, granular and phenotypically Pgp‐1⁻ IL‐2R⁺ B220⁺, (2) CD3⁻‐CD8⁺ IEL express the RAG‐1 gene, and (3) CD3⁻CD8⁻, CD3⁻CD8⁺ and CD3⁺CD8⁺αα IEL, respectively, appear sequentially in normal ontogeny and in bone marrow‐reconstituted thymectomized radiation chimeras. In the latter, virtually all CD3⁺CD8⁺αα IEL expressed the γδ T cell receptor (TCR), but not the αβ TCR. From this and what is presently known about T cell development, we propose that CD3⁻CD8⁺ IEL are an intermediate in extrathymic IEL development and that the development of extrathymically derived IEL occurs at the intestinal epithelium from CD3⁻CD8⁻ to CD3⁻CD8⁺ to CD3⁺(γδ TCR)CD8⁺αα.