Twenty-four children, from 10 to 20 years old, with asthma treated with beta 2-adrenoceptor agonists were matched with healthy controls of the same age, sex, and social background. Stimulated whole and parotid saliva was collected, and decayed and filled tooth surfaces as well as oral hygiene habits were recorded. The dietary and sugar intake was carefully checked by a four-day dietary record. The asthmatic children had a 26% lower (p less than 0.05) value for secretion rate of whole saliva. Seventy percent of the children with Streptococcus mutans counts greater than 2 X 10(5) colony-forming units/mL of whole saliva belonged to the asthmatic group (p less than 0.05). The concentrations of total protein and amylase in parotid saliva were significantly lower for the asthmatic children. The concentrations of potassium, salivary peroxidase, bacteria-aggregating glycoproteins, and secretory IgA were not affected, but the secretion rate of parotid saliva was 36% lower in the asthma group (p less than 0.05). Oral hygiene and dietary habits did not differ between the groups. The asthmatic children had higher DFS scores, but these were not significantly different from those of the healthy controls (p = 0.07). We suggest that subjects with asthma treated with beta 2-receptor agonists should receive special prophylactic attention.