During the last years public Hospitals have experienced a progressive saturation. This has motivated the development of short stay medical units (SSMU) as an alternative to the traditional hospitalization. In our Hospital a SSMU begun to admit patients in April of 1994. During the rest of that year, 1814 were admitted to the unit with a mean hospital stay of 3.22 +/- 2.0 days. 68% of the patients were discharged and 32% were transferred to other units in the Hospital according to their diagnoses. 30% of the patients were seen in an external clinic, by the same medical staff, shortly after the discharge. Since the unit is functioning, the number of ectopic patients of the Department of Medicine decreased to a third and the mean hospital stay of all the medical patients decreased by 3.4 days. We consider that it is possible to achieve a short medical stay with the support of a swift external clinic. The SSMU also improved the allocation of the patients throughout the medical units, and contributed to mitigate the number of the ectopic patients.