Objective: To study the relationship between an impaired blood flow response after a local cold stimulus, testing nerve regulation of the local blood flow response, and an increased risk of developing pressure ulcers. Design: An observational, longitudinal, prospective study. Setting: Dutch nursing home. Patients: Eighty-two newly admitted somatic nursing home patients, age 60 years and older. Intervention: A local cold stimulus (17°C) applied to the trochanter major. Main Outcome Measures: On admission, blood flow response to a local cold stimulus. As the stimulus was withdrawn, the temperature measured at the skin increased asymptotically toward the final temperature, TfThe velocity of this rise was characterized by the time constant, τ, of the process. On admission, and weekly during a 4-week follow-up period, the presence or absence of pressure ulcers was verified. Results: The blood flow response time correlated significantly with the risk of developing pressure ulcers. The patients who developed pressure ulcers during the follow-up period had a significantly longer response time than the patients who did not. Conclusions: Malfunction of the nervous regulatory mechanisms of the local blood flow is partially responsible for an increased susceptibility to pressure ulcer formation.