Rabbit antisera were raised to six synthetic peptides corresponding to amino acid sequences contained in the protein product of the cystic fibrosis gene, CFTR. For two peptides, [Lys102]CFTR(102-116) and CFTR(1468-1480), antibody-peptide binding was of high affinity in that half-maximal binding occurred at peptide concentrations below 10 nM. Monospecific antibodies were prepared using these peptides, and these antibodies were used to stain human skin. Specific staining was detected in the cells lining the reabsorptive duct of the sweat gland. Within these lumenal cells, staining was most prominent at the apical domain but was also detected near the basolateral surface. This finding agrees well with predictions based on the effects of cystic fibrosis on sweat gland function, and suggests that these antibodies will be useful for studying CFTR in other human tissues.