BACKGROUND: Older adults with panic disorder and agoraphobia (PDA) are underdiagnosed and undertreated, while studies of cognitive-behavioral therapy (CBT) are lacking. This study compares the effectiveness of CBT for PDA in younger and older adults. METHODS: A total of 172 patients with PDA (DSM-IV) received manualized CBT. Primary outcome measures were avoidance behavior (Mobility Inventory Avoidance scale) and agoraphobic cognitions (Agoraphobic Cognitions Questionnaire), with values of the younger (18-60 years) and older (>/= 60 years) patients being compared using mixed linear models adjusted for baseline inequalities, and predictive effects of chronological age, age at PDA onset and duration of illness (DOI) being examined using multiple linear regressions. RESULTS: Attrition rates were 2/31 (6%) for the over-60s and 31/141 (22%) for the under-60s group (chi(2) = 3.43, df = 1, P = .06). Patients in both age groups improved on all outcome measures with moderate-to-large effect sizes. Avoidance behavior had improved significantly more in the 60+ group (F = 4.52, df = 1,134, P = .035), with agoraphobic cognitions showing no age-related differences. Baseline severity of agoraphobic avoidance and agoraphobic cognitions were the most salient predictors of outcome (range standardized betas 0.59 through 0.76, all P-values