We studied the effect of closing a six-bed intermediate care area (ICA) on utilization of a multidisciplinary critical care unit (CCU). Data were collected on all admissions to the 7-bed CCU for 9 months prior to ICA closure (n = 217) and compared with 9 months after CCU expansion (7 to 9 beds) and ICA closure (n = 407). Nonemergency CCU admissions increased from 41 to 112 after ICA closure (p < 0.03). Mean APACHE II score within 24 h of admission decreased from 21.9 +/- 7.4 to 18.6 +/- 7.4 (p < 0.0001). The proportion of patients with APACHE II score < 15, increased from 30/217 to 136/407 accounting for an increase from 5.4 percent to 12.7 percent of CCU days (p < 0.0001). Nursing workload at the time of discharge from CCU decreased (p < 0.0001). The ICA closure altered CCU admission and discharge decision-making. "Low-risk" admissions increased and patients remained in the CCU until they required less nursing care. One factor determining utilization of a CCU is the facilities available outside the unit. A CCU management system is especially important when a wide range of illness severity is present.