Chlorhexidine (CHX) is a compound with plaque-inhibiting effects and available only by prescription in the United States. In Norway, however, CHX has been dispensed over-the-counter for over 20 years, and this study was undertaken to evaluate dentists' perceptions regarding its indications, usefulness, and side effects. A written questionnaire was sent to a sample of 10% of dentists registered in Norway, 78% of whom (354) responded. Additionally, representatives from 2% of all dental practices in Norway were contacted by telephone. Fourteen percent (14%) of the respondents reported that they never recommended CHX to their patients. Among those recommending the compound, 85% used it frequently after surgical periodontal procedures; 74% when treating acute gingivitis; 57% following oral surgery in general; and 35% during non-surgical periodontal therapy. It was used also as an adjunct to other treatment routines. Seventy-three percent (73%) reported frequent use of CHX when treating stomatitis and 54% in herpes simplex infections. As to side effects, 77% of the dentists indicated that staining of teeth, restorations, and the tongue was a major concern to patients; 12% reported inconveniences due to the bitter taste; and 6% reported other disturbances such as dryness of the mouth and development of oral ulcerations. The majority (94%) of the dentists recommended mouth rinsing, whereas 6% recommended a gel form. Only 4% of the dentists recommended rinsing with a patient-diluted 0.1% concentration, whereas 96% recommended the standard 0.2% formulation; 88% recommended using CHX mouthwash twice a day or more often.(ABSTRACT TRUNCATED AT 250 WORDS)