Background Since the introduction of cognitive behaviour therapy (CBT), researchers are searching for the optimum schedule of sessions to maximize the effectiveness. In the last decades, intensive treatments - multiple long sessions in a few weeks - became popular in patients with anxiety disorders and obsessive-compulsive disorder (OCD). However, it is still unknown whether intensive CBT is superior to regular CBT (short weekly sessions for several months). Methods This meta-analysis examined whether intensive CBT is superior to regular CBT in patients with anxiety disorders and OCD in reducing anxiety, obsessivecompulsive (OC) and comorbid depressive symptoms, and in reducing dropout. A systematic literature search was performed in PubMed, PsycINFO and Embase in which words indicative of an anxiety disorder or OCD were combined with intensive treatment and CBT. Results We identified 5012 unique studies. Two randomised controlled trials (RCTs) and four non-RCTs were included, pertaining to 393 subjects. Intensive CBT and regular CBT did not statistically differ in reducing anxiety or OC symptoms from pre- to post-treatment and from post-treatment to follow-up. However, intensive CBT was significantly better in reducing depressive symptoms from pre- to post-treatment (g=0.25; 95% CI: (0.04, 0.45)). Dropout was only reported in two studies and could thus not be meta-analysed. Limitations The included studies were limited in number and quality. Conclusions High-quality RCTs are needed to assess both effectivity and feasibility of intensive CBT. Meanwhile, intensive CBT might be preferable for patients with comorbid depression or for those needing fast improvement, due to its shorter lead time.