We carried out a prospective study to determine the association between immobilization in the immediate postinjury period and the development of pressure ulcers in spinal cord-injured patients following their admission to Charity Hospital, New Orleans. Of 39 patients consecutively admitted to the hospital, 23 (59%) developed a grade one ulcer within 30 days, mostly in the sacral region (57%), the peak time of onset being day 4 postinjury (6/23 cases). In partial support of an earlier retrospective study (Linares HA, Mawson AR, Suarez E, Biundo JJ Jr: Association between pressure sores and immobilization in the immediate post-injury period. Orthopedics 1987;10:571-573), duration of unrelieved pressure prior to ward admission was significantly associated with ulcers developing within the first eight days of injury (P = 0.04), but not with ulcers developing during the entire 30-day observation period (P = 0.09). Time on the spinal board was also significantly associated with ulcers developing within 8 days (P = 0.01), but not with ulcers developing within 30 days (P = 0.09). An unexpected finding was the significant inverse association between systolic blood pressure and the development of ulcers both within 8 days (P = 0.03) and within 30 days (P = 0.02), suggesting that reduced tissue perfusion increases the spinal cord-injured patient's susceptibility to pressure ulcers.