Leucine-rich repeats (LRRs) are 22-28 amino acid long sequence motifs found in a variety of extracellular, membrane and cytoplasmic proteins. They are believed to mediate specific protein-protein interactions and to function in cellular adhesion. In Drosophila, four LRR proteins are known and each plays an important role in embryogenesis. In this paper we report the cloning of a cDNA that encodes a fifth Drosophila embryonic LRR protein, LRR47. The sequence includes a hydrophobic N-terminal which may constitute an ER signal sequence, eight LRR copies and a unique C-terminal. The transcript of the LRR47 gene is detected in adult females and in early embryogenesis. It is not found in adult males and is only present at low levels in embryos after 6 h of development. In Western blot experiments, a protein of approx. 47 kDa, which is expressed in a similar developmental profile and purifies in peripheral membrane protein extracts, is detected by an antibody specific for LRR47. The LRR47 gene maps to position 32A on the left arm of chromosome 2, an interval in which three genes with semi-lethal maternal effects (dal, hup and wdl) are located.