Introduction The effect of mental and behavioural disorders (MBD) on the risk of tendon ruptures after flexor tendon repair is not well understood. This study aimed to analyse the association between MBD and tendon rupture after flexor tendon repair in zones I and II.Methods Data from the Swedish National Registry for Hand Surgery (HAKIR) on patients with a complete flexor tendon repair at our department between 2012 and 2019 were followed for a minimum of 2 years to assess the rate of rupture. Independent variables were collected from HAKIR and clinical records: prevalence MBD based on ICD-10 codes F0-F99, age, sex, injured tendon, number of injured fingers, day to surgery, core suture, digital nerve injury, smoking, injury mechanism, and rehabilitation method. Multiple logistic regression was used to assess the association between variables.Results A cohort of 593 patients with 49 ruptures (8.2%) was identified. Potential causes of rupture were non-adherence behaviour in 16 (33%), accidents in seven (14%), infections in six (12%), and no clear cause in 20 (41%) patients. Patients with MBD had an association to rupture (OR 3.6), 17.7% ruptures compared to 7.2% in patients with no diagnosed disorders. Patients >50 years of age had a higher risk compared to patients <25 years (OR 4.3), 15% compared to 3.9%' respectively. Men had a higher risk compared to women (OR 2.9), 10% compared to 4.3%' respectively.Conclusion We identified an association between the prevalence of mental and behavioural disorders and rupture after flexor tendon repair.