Psychiatric consultation in primary care as well as in the hospital is both effective and cost-effective if certain procedures are followed. With the professional guideline 'Consultation psychiatry', the Dutch Psychiatric Association aims at setting a standard for psychiatric consultations in non-psychiatric settings. In general practice, the psychiatric consultation is preferably embedded in 'collaborative care', an integrated care model including the general practitioner and a case manager (usually a nurse), with the consultant psychiatrist being regularly available for clearly defined indications. The psychiatrist should see the patient himself or herself, establish a diagnosis and treatment plan, and provide the general practitioner and the patient with a so-called 'consultation letter', which is then discussed with both. In a general hospital, systematic screening of patients at risk of psychiatric comorbidity can be organised. Early detection of complex patients can further improve the effectiveness of psychiatric consultation. Follow-up contacts and investing in liaison contacts improve adherence to the advice provided.