Introduction: Health anxiety, also known as 'hypochondriasis', is a common, distressing and costly condition that responds to cognitive behavior therapy (CBT) but evidence pertaining to response and remission rates, treatment in routine care, therapist-guided Internet-delivered CBT (ICBT) and health economics has not been systematically reviewed.Areas covered: In this systematic review and meta-analysis we searched PubMed, PsycINFO, and OATD (17/06/2019) for randomized controlled trials (RCTs) comparing CBT to non-CBT controls for health anxiety. Based on 19 RCTs, the pooled between-group effect on health anxiety was moderate to large (g = 0.79; 95% CI: 0.57-1.01; adjusted for publication bias: g = 0.62), with small to moderate effects on secondary symptoms and effects largely sustained 12-18 months after treatment. Moderators were control condition and recruitment path, but not treatment setting. The pooled CBT response rate was 66%, and the remission rate 48%. ICBT had effects comparable to face-to-face CBT. CBT for health anxiety is probably cost-effective, but with limited effect on the quality of life.Expert opinion: CBT is a highly efficacious and probably cost-effective treatment for health anxiety. We recommend that ICBT is implemented more widely, and that health economic outcomes and ways of increasing response and remission rates are explored further. Keywords: Cognitive behavior therapy; cost-effectiveness; efficacy; health anxiety; hypochondriasis; systematic review.