We describe a method for culturing human airway smooth muscle. Cells were enzymatically and mechanically dispersed from strips of smooth muscle harvested from surgically removed lobar bronchi, and were seeded on to dishes containing Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum. After 14-21 days confluent monolayers of cells formed, which were subcultured and identified as smooth muscle by positive immunocytochemical staining for actin and myosin. The retention of functional plasmalemmal receptors and of intracellular signal transduction pathways in cell culture was demonstrated in 45Ca-labelled monolayers by the stimulation of efflux of intracellularly stored 45Ca in response to extracellularly applied 10 microM carbachol or 10 microM histamine. Human airway smooth muscle in cell culture provides a novel preparation for investigating the physiology and pathophysiology of the human airways.