The present study examines the extent of spinal cerebrospinal fluid (CSF) absorption in healthy individuals in relation to physical activity, CSF production, intracranial pressure (ICP) and spinal CSF movement. Thirty-four healthy individuals aged 21-35 years were examined by lumbar puncture and radionuclide cisternographies with repeated imaging. ICP was registered previous to and after CSF drainage and CSF production was calculated. Spinal CSF absorption was calculated as reduction in spinal radionuclide activity. The radionuclide activity in the spinal subarachnoidal space (SAS) was gradually decreased by 20 ± 13 % (mean ± SD) during one hour. The reduction was higher in active than in resting individuals (27 ± 12 % vs. 13 ± 9 %, mean ± SD). The mean ICP in 19 of the individuals was 13.6 ± 3.1 (± SD) cm H₂O. B-waves were found in 79 % of the individuals with a mean frequency of 0.6 ± 0.3 (± SD) / minute. The mean CSF production rate was 0.34 ± 0.13 (± SD) ml / minute. There were no correlations between radionuclide reduction, spinal movement of the radionuclide and CSF production rate. The spinal radionuclide reduction found in this study indicates a spinal CSF absorption of 0.11 - 0.23 ml / min, more pronounced in active than in resting individuals.