Psychiatric illnesses have a high prevalence in the general population. Psychiatric illnesses affect the way other medical processes develop: age of onset, distribution by gender, type an evolution, and the training of the psychiatrists in caring for them.

To describe the characteristics and the medical problems of patients who have been consulted by an Internal Medicine Liaison Unit while hospitalized in the Psychiatric Unit of a third level hospital. Comparison of the general profile of these patients and their consultations with that done to patients hospitalizad in the rest of the hospital.

Descriptive retrospective study from September 2007 to May 2010. Use of a centralized database created with of all the administrative and clinical details regarding the consultation. A p ≤ 0.05 has statistical significance.

648 patients were identified (40,7% men). Mean age 52.4 years. Mean stay 3 days. 34,4% were solved in one visit. Mortality rate 0,3%. 94,1% of discharges were due to recovery, the rest were transfered to another service.

Distribution by major diagnostic groups: infectious 16,2%, cardiorespiratory 15,4%, mental illness 12,9%, metabolic 10,4%, tumoral 8,5%, digestive 8,2%, not defined 8,2%, hematologic 5%, others 15,2%.

The psychiatric patient is clearly younger and the female gender is slightly higher (59,3%) than in the control group. In this group the infectious and cardiorespiratoty illnesses predominate. The percentage of psychiatric consultations (34,1%; 648) over our global (1906) is impressive since the number of psychiatric inpatients is not proportional to this number.