Thymic development of [alpha][beta] T lymphocytes into invariant natural killer (NK) T cells depends on their selection via agonistic lipid antigen presented by CD1d. If successful, newly selected NKT cells gain effector functions already in the thymus. Some [gamma][delta] T cell subsets also acquire effector functions in the thymus. However, it is not clear whether agonistic TCR stimulation is involved in thymic [gamma][delta] T cell selection and development. Here we combine two genetic models to address this question. MiR-181a/b-1.sup.-/- mice, which show impaired agonistic T cell selection of invariant [alpha][beta] NKT cells, were crossed to Tcrd-H2BeGFP reporter mice to monitor selection, intra-thymic expansion and differentiation of [gamma][delta] T cells. We found that miR-181a/b-1-deficiency had no effect on numbers of thymic [gamma][delta] T cell or on their differentiation towards an IL-17- or IFN-[gamma]-producing effector phenotype. Also, the composition of peripheral lymph node [gamma][delta] T cells was not affected by miR-181a/b-1-deficiency. Dendritic epidermal [gamma][delta] T cells were normally present in knock-out animals. However, we observed elevated frequencies and numbers of [gamma][delta] NKT cells in the liver, possibly because [gamma][delta] NKT cells can expand and replace missing [alpha][beta] NKT cells in peripheral niches. In summary, we investigated the role of miR-181a/b-1 for selection, intrathymic development and homeostasis of [gamma][delta] T cells. We conclude that miR-181a/b-1-dependent modulation of T cell selection is not critically required for innate development of [gamma][delta] NKT cells or of any other [gamma][delta] T cell subtypes.