EFT-Tapping has been extensively investigated for anxiety and depression. 

In the first large-scale study of 5,000 patients seeking treatment for anxiety across 11 clinics over a 5.5-year period, an improvement was found in 90% of patients who received Tapping therapy compared to 63% of those who received cognitive behavioral therapy (CBT). Complete relief of symptoms was seen in 76% of people in the EFT group compared with 51% of people in the CBT group. One year later, the improvements seen were maintained by 78% of the EFT group compared with 69% of the CBT group. 

Research comparing EFT to CBT for patients diagnosed with major depressive disorder, found after 8 weeks of group treatment (16 hours), both interventions produced significant reductions in depressive symptoms. The CBT group indicated a significant reduction after the intervention, but this was not maintained over time. The EFT group however, showed a delayed effect of significant reductions in depressive symptoms at 3- and 6-month follow-ups. Learn more via the National Institutes of Health's National Library of Medicine (NIH/NLM):

EFT for Anxiety:

EFT for Depression:

EFT for PTSD: