OBJECTIVES: To evaluate a stepwise approach to chronic cough that emphasized initial treatment of all patients with an antihistamine-decongestant for postnasal drip and to determine the value of routine bronchoprovocation challenge in the evaluation of chronic cough. DESIGN: Prospective trial using an algorithm for chronic cough in immunocompetent nonsmoking out-patients. SETTING: University-based pulmonary practice. PATIENTS: Forty-five patients met the inclusion criteria. The mean duration of cough was 140 weeks (range, 3 to 2080 weeks), and the mean severity of cough as assessed by patients on a four-point scale was "severe." RESULTS: Marked improvement and resolution (mean, 3.1 and 7.1 weeks, respectively), with resolution in 96% of patients. Antihistamine-decongestant therapy was beneficial in 39 of 45 patients and was the only therapy needed for 16 patients. Bronchoprovocation challenge had a negative predictive value of 100% and a positive predictive value of 74% for cough caused by asthma. No significant relationship was found between the time to cough resolution and duration or severity of cough. Eighteen percent of patients experienced a recurrence of cough at a follow-up interval of 3 months. CONCLUSIONS: A sequential approach to chronic cough that emphasizes initial treatment with an antihistamine-decongestant is effective. Bronchoprovocation challenge is useful in evaluating patients with chronic cough but can be delayed until the initial response to antihistamine-decongestant therapy has been assessed. The 18% incidence of recurrence highlights the fact that cough often is the manifestation of a chronic or recurring process that requires chronic or episodic therapy.