The human rhabdomyosarcoma cell line TE671 expresses the foetal subtype of muscle acetylcholine receptor (AChR). By transfecting TE671 cells with cDNA encoding the human muscle AChR epsilon subunit under the control of the cytomegalovirus promoter we have established a stable cell clone that, in addition, constitutively expresses the adult AChR subtype. Both subtypes are inserted into the plasma membrane and demonstrate their respective characteristic single channel properties. The level of expression of the adult AChR subtype is two- to three-fold higher than that of the foetal subtype. The new cell clone provides a relatively abundant source of human adult AChR for immunological and pharmacological investigations.