Spinal cord blood flow (SCBF) was measured in the primate thoracic spinal cord using the 14C-antipyrine autoradiographic technique that allowed clear differentiation between white and gray matter blood flow. Individual SCBF values were obtained for 0.1-sq mm areas of the thoracic cord cross section. White matter blood flow was homogeneous throughout with a mean value of 10.3 +/- 0.2 ml/100 gm/min. Gray-matter flow was more variable with lower values in the dorsal horns and higher values in the central gray and anterior horns. Mean gray-matter flow was 57.6 +/- 2.3 ml/100 gm/min. Arterial pO2 was 123 +/- 2 torr, pCO2 was 40.2 +/- 0.5 torr and pH was 7.327 +/- 0,010. Mean arterial blood pressure was 113 +/- 3 mm Hg and core temperature was 36.4 degrees +/- 0.1 degrees C.