Patient tests in hospital environments involve a significant percentage of hospital resources. The patient must occupy some of his/her time, personnel and equipment have to be allocated, co-operation between hospital laboratories and departments must be ensured, tests should be performed within rigid time limits and the results should be ready before due times imposed by doctors, nurses or other medical personnel. From the patient's point of view there must be almost no distress, while hospital management wants as much equipment utilization as possible. In the present paper we propose a system for efficient scheduling of patient tests, while obeying all temporal and managerial limitations as well as observing all medical procedures. This system, which we call HOSTESS, uses a new approach, the dynamic distributed scheduling for managing the patient test requests in large hospitals, with many laboratories that perform a multitude of tests. The system is designed as a modular expandable application, in order to perform efficiently under heavy loads. Doctors, nurses, laboratory technicians and other personnel enter their requests and HOSTESS creates consistent schedules for every equipment needed in the required tests.