We report the cloning of a full-length cDNA from the plant-parasitic nematode Meloidogyne incognita, which encodes a putative protein of 1082 amino acids showing high similarity with K-Cl cotransporters (KCCs) from the free-living nematode Caenorhabditis elegans (54% identity) and from a number of mammals, including human. Hydropathy analysis indicates typical KCC topology patterns, with a hydrophylic NH2-terminal region, 12 membrane-spanning domains, and a long COOH-terminal hydrophylic region. Alignment of the nematode sequences with eleven KCC sequences from mammals suggests that the nematode proteins may constitute a separated family of KCCs. The M. incognita gene was shown to be expressed in both motile and sedentary stages, which suggests an important function in general physiology of the nematode. By analogy with known proteins, it is hypothesized that this gene is involved in the regulation of cell osmotic pressure to maintain nematode body fluids hyperosmotic to the environment.