The frequency and type of oral mucosal lesions, dental infections, and salivary constituents were evaluated in 53 patients with Crohn's disease, who were divided into inactive, mildly active, and severely active groups on the basis of clinical and endoscopic criteria. Buccal biopsies from nine patients with active disease showed morphologic changes that suggested Crohn's disease-related lesions. Panoramic radiographs revealed more infectious foci in the teeth of patients with active Crohn's disease than in patients with inactive disease. Salivary flow rate, buffering capacity, total protein, amylase, and IgA and IgG concentrations did not differ with respect to the activity of Crohn's disease. The observed mucosal inflammation in patients with active Crohn's disease, although high in frequency, was mild and did not need therapy, but the great number of dental infections in association with the activity of Crohn's disease should be taken into account in the treatment of these patients.