This study was conducted to determine (1) if serum creatinine levels (SCL) in spinal cord injury (SCI) patients are influenced by neurologic level of lesion, sex, age, or time since injury, and (2) if SC values are a sensitive indicator of renal function (as reflected by renal plasma flow [RPF]) in these patients. The overall SC mean and SD were 0.9 +/- 0.2mg/dl (n = 141). There was no difference in SC values between patients with higher injuries (T-6 or above) and patients with lower injuries (T-7 or below), nor was there any difference between patients with lesions less than 3 months, 10-14, 22-26, 34-38, 46-50, or 58-62 months in duration. Age and gender each accounted for less than 5% of the variation in SC. There was no significant correlation between RPF and SC (unless the patient also had moderate or severe pyelocaliectasis) nor between change in serum RPF (from the previous examination, usually 12 months earlier) and change in SC, suggesting that SCL does not reflect the functional status of the kidney in these patients.