The possibility to administer chemo-hormone- and immunotherapy on an out-patient basis has greatly increased because of the progress reached in the management of the out-patient departments. The improved knowledges on tossicological, pharmacodynamic and therapeutic data as well as the advent of the cyclic schedules determined the feasibility of medical treatments even when they are combined with surgical and/or radiotherapeutic modalities. To the patient, the possibility to be carefully and effectively treated on out-patient clinic, renders more acceptable, both from a psychologic and economic point of view, even a prolonged combined treatment. On the same time, also the Institutions have some advantages both on their organization (a shorter median stay in hospital and consequently a reduced waiting list) and for their scientific program (increased number of patients who can be treated according to a therapeutic program, possibilities to obtain statistically valuable information on the treatment program of a given disease and on the knowledge of its natural history). The last five year increasing activity of the Out-Patient Clinic for Medical Oncology Treatment of the Istituto Nazionale Tumori of Milan is illustrated in Text-figure 1, while Text-figure 2 represents its actual organization; this is obviously of a multidisciplinary type, both on its diagnostic and therapeutic phase. Table 1 shows the activity carried out in 1975; it is noteworthy that 2,570 patients have been followed, thus accounting for a total of 20,164 medical examinations and/or intravenous drug administrations. Table 2 presents the incidence of the different types of neoplasia followed in the out-patient department: the large majority was represented by breast cancer (40%); followed by malignant lymphomas (31.5%) and pediatric tumors (7.5%). During 1975, 22 therapeutic protocols have been applied, 10 of which (table 4) required an initial hospitalization and 12 (table 5) could be entirely carried out in the out-patient department. As shown in Table 6 chest x-rays accounted for 52% and skeletal survey for 18% of the 11.906 radiological examinations. Table 7 shows the number of off-hand required radiological reports carried out for patients not geographically accessible who, in one signle day, could have their radiological, and medical examinations as well as their hemogram and treatment performed. A total 467 scintiscans have been required, 86% of which of the liver (table 8). The hemato-pathology unit counted out about 16,000 hemograms with platelets (table 9). The hemograms were always performed within 1-2 hours with immediate communication of the counts to the out-patient department. In order to modify clinical situations which were deteriorated because either of the disease or of the treatment 358 blood units were transfused.