Few studies have explored psychological factors associated with body image dissatisfaction in individuals seeking aesthetic surgery on the NHS. In NHS Scotland, The Adult Exceptional Aesthetic Referral Protocol (AEARP) states that individuals are only eligible for consideration for surgery where there is significant psychological distress and physical criteria associated with perceived problem of appearance. The AEARP necessitates that individuals seeking aesthetic surgery on the NHS must have a psychological assessment. It is therefore crucial to identify psychological factors associated with body image dissatisfaction that may highlight contraindications for surgery or are amenable to psychological intervention. A total of 311 consecutive patients seeking aesthetic surgery who were referred for psychological assessment under the AEARP completed a series of psychometric measures as part of routine clinical practice. Multiple mediation analyses using bootstrapped method was used to explore the relationship between interpersonal functioning, emotion regulation, perfectionism, and body image dissatisfaction. Multiple mediation analysis indicated that emotion regulation partially mediates the relationship between interpersonal functioning and body image dissatisfaction in this clinical population. This study indicates that interpersonal functioning and emotion regulation significantly relate to body image dissatisfaction in this patient group. Psychological assessment of patient suitability for aesthetic surgery should include assessment of interpersonal functioning and emotion regulation which may be amenable to psychological intervention and be of significant benefit to patients either pre- or post-operatively or instead of surgery.