The slc4 and slc26 gene families encode two distinct groups of gene products that transport bicarbonate and other anions in mammalian cells. Slc4 and slc26 proteins are important contributors to trans-epithelial movement of fluids and electrolytes and to cellular pH and volume regulation. Here we describe the cDNA cloning from the nematode C. elegans of four abts (Anion Bicarbonate TranSporter) homologs of slc4 cDNAs, and eight sulp (SULphate Permease) homologs of slc26 cDNAs. Analysis of transgenic nematode strains carrying promoter::GFP fusions suggests relatively restricted expression patterns for many of these genes. At least three genes are expressed primarily in the intestine, three genes primarily in the excretory cell, and one gene is expressed in both of these polarized cell types. One of the genes is also expressed exclusively in the myoepithelial-like cells of the pharynx. Many of the sulp gene products localize to the basolateral rather than to the apical membrane. Several ABTS and SULP proteins exhibited anion transport function in Xenopus oocytes. The strongest Cl^- transporter among these also mediated Cl^-/HCO₃^- exchange. These findings encourage exploitation of the genetic strengths of the nematode model system to study the physiological roles of anion transport by the proteins of these two highly conserved gene families.