Salivary bicarbonate and epidermal growth factor (EGF) have an important protective role in the oesophagus. The effect of smoking cessation on these aspects of salivary function is unknown. Salivary bicarbonate secretion and EGF output were measured before and after attempted smoking cessation in 28 healthy volunteers. Urinary cotinine excretion was used to assess compliance. Negative correlations were found between salivary flow rate and age (rho = -0.34) and between cigarette consumption and salivary flow (rho = -0.27) and salivary bicarbonate concentrations (rho = -0.32). Smoking cessation was associated with a significant increase in salivary bicarbonate secretion (day 0, 1.7 (0.14-6.2); day 7, 3.6 (0.52-6.4); day 21, 3.3 (0.44-6.6) micromol min(-1); P < 0.01) but left salivary EGF output unchanged. Smoking cessation is associated with significant improvements in salivary bicarbonate secretion. This would benefit patients with reflux disease who stop smoking.