Despite the established role for PI3Ks in cell migration, the PI3Ks involved in lymphocyte chemotaxis are poorly defined. In this study, we report that p110gamma-deficient T cells, but not B cells, show reduced chemotactic responses to the lymphoid chemokines, CCL19, CCL21, and CXCL12. As B cell and T cell chemotactic responses were both sensitive to the general PI3K inhibitors, wortmannin (WMN) and LY294002, we explored whether B cell responses were affected in mice lacking p110delta, a major PI3K isoform in lymphocytes. B cells deficient in p110delta showed diminished chemotactic responses, especially to CXCL13. Adoptive transfer experiments with WMN-treated wild-type B cells and with p110delta-deficient B cells revealed diminished homing to Peyer's patches and splenic white pulp cords. WMN selectively inhibited CXCR5-dependent B cell homing to Peyer's patches. These observations establish that p110gamma and p110delta function in lymphocyte chemotaxis, and show differential roles for PI3K family members in B and T cell migration.