Conj Assoc Prof Wijeratne is a psychiatrist with clinical expertise in severe mood disorders, neurocognitive disorders, and the assessment of capacity. He has a longstanding interest in doctors' health, in particular late career practitioners and doctors from an ethnically and racially diverse background, and in medical regulation given his work as an assessor for the Medical Council of NSW. He has been involved in research in a variety of other areas, including functional somatic syndromes which was the subject of his postgraduate research degree, late life bipolar disorder, and currently intimate partner violence in older people and psychogeriatric syndromes in the oldest old.