Temporary observation is a very short stay in Emergency Department, widely carried out in adult patients in our Country. No experience in childhood has been reported. In our emergency department children under 16 with acute diseases are admitted for 24-48 hours. From 1991 we carried out also temporary observation. Its effectiveness has been evaluated by studying our activity in 1992 (14.574 emergency room visits, with 664 admissions to our Department and 274 temporary observation) and 1993 (12820 emergency room visits, 573 admissions, 428 temporary observation). Compared to 1992, in 1993 there was a decrease of both emergency room visits (higher than expected from demographic lowering and in part due to payment for emergency room visits) and hospital admissions, and an increase of temporary observation. The stay in hospital was less than 6 hours in 94.2% of temporary observation patients. 18.2% of them were evaluated on clinical basis, 57% also by diagnostic examinations, 24.8% had some treatment. The 89% of the children were sent home following temporary observation, the others were admitted. Criteria for temporary observation were fairly similar to those for hospital admission, but not far as Central Nervous System and Renal Disease are concerned. Our study confirms the usefulness of temporary observation in childhood to reduce both the number of hospital admissions and the discomfort of the patient and his family. Nevertheless there is a need of criteria of appropriateness. Therefore we have elaborated guide lines for temporary observation and admission to our Department.