['Airway hyperresponsiveness (AHR) is associated with persistent air flow limitation and accelerated FEV(1) decline. AHR can influence diagnosis, treatment, and prognosis. We assessed the value of pulmonary function variables, symptoms, and history as selection criteria for methacholine bronchoprovocation testing to detect AHR in symptomatic subjects.', 'Over a 4-year period we conducted a prospective study of consecutive subjects who underwent methacholine bronchoprovocation testing. Baseline pulmonary function testing (PFT) and a questionnaire were obtained prior to methacholine bronchoprovocation testing. PFT and symptom and history variables were assessed as AHR predictors in univariate and multiple logistic regression analyses for the whole group and for 4 different age groups.', 'There were 530 subjects, with ages ranging from 5 to 87 years, and 232 (44%) were positive for methacholine AHR. AHR was more prevalent among subjects < or = 25 years old (59%) and > 65 years old (47%) than among the other age groups. PFT values, symptom, and history variables had different AHR predictive values among the different age groups. Symptom and history variables had no AHR predictive value among subjects < or = 25 or > 65 years old.'] Are clinical variables poor selection criteria for the use of methacholine bronchoprovocation in symptomatic subjects?