The Drosophila Akt (dAkt) serine/threonine kinase is a component of the insulin receptor/PI3K signaling pathway that regulates cell growth. Here, we show that this kinase is expressed during Drosophila oogenesis and is required for egg chamber development. Loss of dAkt function in follicle cells causes a cell-autonomous reduction of cell size while expression of the constitutively active myristylated form of this kinase (dAktmyr) causes increased cell size. Accordingly, expression of the antagonist dPTEN in the same follicular domains causes reduced follicle cell size. Perturbations of dAkt function do not affect follicle cell proliferation or cell death. Of interest, expression of dAktmyr in the posterior domain of the follicular epithelium causes a delay in the posterior movement of follicular epithelium and dumpless-like egg chambers. It appears that dAkt is required for maintaining the continuity of cell size within the follicular epithelium, which in turn is necessary for its proper morphogenesis. Developmental Dynamics 232:845–854, 2005. © 2005 Wiley-Liss, Inc.