Human bronchi have been investigated in vitro without or after storage at -196 degrees C in different media containing 1.8 M dimethyl sulfoxide and 0.1 M sucrose as cryoprotectants, dissolved in either fetal calf serum (FCS), Krebs-Henseleit solution (KH), or 50% FCS in KH as vehicles. As assessed by the post-thaw responses to both carbachol and histamine, optimal preservation of contractile responsiveness was obtained with bronchi that had been frozen in a medium containing KH solution as the vehicle. With each group of cryopreserved bronchi, maximal responses to relaxant agonists such as isoprenaline, papaverine, and the potassium channel activator bimakalim were attenuated by up to 50%, and the passive resting tension after maximal pharmacological relaxation was considerably higher than in the unfrozen tissues. The evidence suggests that, despite some reduction in elasticity, cryopreservation of human bronchi at -196 degrees C preserves both contractile and relaxant mechanisms and offers clear potential for storing human airway smooth muscle for subsequent pharmacological experiments.