People with epilepsy are significantly more likely to have a mental health disorder than those without a chronic illness. The reasons for this are multiple but may include the mental health difficulties being perceived as complex due to the presence of a chronic illness. In part due to the apparent complexity of the co-occurring physical and mental illness, many are not offered evidence-based treatment (EBT) for the mental health disorder. There is little guidance to inform clinicians about the interventions to use to treat mental health disorders in people with epilepsy. The present paper reports a case of treatment for depression using a standard EBT in a young person with epilepsy. The patient also had clinically significant symptoms of anxiety and an eating disorder and would be considered ‘complex’ according to standard criteria. The intervention, however, was relatively simple and was delivered as guided self-help via 10 weekly telephone calls of approximately 30 minutes duration, and two follow-up calls at one month and three months post-intervention. Self-report and parent-report questionnaire measures were completed before and after the intervention, and at both follow-up time points. A blind-rated online diagnostic interview measure was also completed before and after the intervention. The young person and her family also completed a qualitative interview of their experiences of the intervention. This simple intervention was effective in working towards the client's goals, although pre–post measurement on standard measures was variable. This interesting case raises questions about whether patients with mental and physical comorbidities are complex, or just perceived as complex.