BackgroundEffective transdiagnostic treatments for patients presenting with principal or comorbid symptoms of anxiety and depression enable more efficient provision of mental health care and may be particularly suitable for the varied population seen in primary healthcare settings. Mindfulness-integrated cognitive behavior therapy (MiCBT) is a transdiagnostic intervention that integrates aspects of CBT, including exposure skills targeting avoidance, with training in mindfulness meditation skills adopted from the Vipassana or insight tradition taught by the Burmese teachers U Ba Khin and Goenka. MiCBT is distinguished from both cognitive therapy and mindfulness-based cognitive therapy by the use of a theoretical framework which proposes that the locus of reinforcement of behavior is the interoceptive experience (body sensations) that co-arises with self-referential thinking. Consequently, MiCBT has a strong focus on body scanning to develop interoceptive awareness and equanimity. Designed for clinical purposes, the four-stage systemic approach of MiCBT, comprising intra-personal (Stage 1) exposure (Stage 2), interpersonal (Stage 3), and empathic (Stage 4) skillsets, is a distinguishing feature among other mindfulness-based interventions (MBIs). The aim of this study is to investigate whether and how group MiCBT decreases depression and anxiety symptoms for patients with a range of common mental health conditions.MethodsParticipants (n = 120) recruited via medical practitioner referral will be randomized to MiCBT or a wait-list control. Inclusion criteria are age 18–75; fluent in English and having a Kessler Psychological Distress Scale (K10) score of 20 or more. The MiCBT treatment group receive an 8-week MiCBT intervention delivered in a private psychology practice. Participants complete a suite of online self-report measures and record the amount of meditation practice undertaken each week. The control group receive usual treatment and complete the measures at the same time points. Primary outcome measures are the Depression Anxiety Stress Scale-21 (DASS-21) and K10. Analysis will use mixed-model repeated measures.DiscussionThe potential ability of MiCBT to provide a comprehensive therapeutic system that is applicable across diagnostic groups would make it an attractive addition to the available MBIs.Trial registrationThis trial is registered with the Australia and New Zealand Clinical Trials Registry: ACTRN12617000061336; Date of registration: 11th January 2017.