A search for spontaneous retinal venous pulsations was carried out in 218 subjects. Spontaneous venous pulsations were present in 87.6% of 146 unselected subjects 20 to 90 years of age and absent in 100% of 33 patients with raised intracranial pressure without papilledema and ten patients with papilledema. Lumbar puncture in nine patients with raised intracranial pressure established the upper level at which spontaneous pulsations disappear as 190 mm H2O, and no pressure above 180 mm H2O was found in 29 patients with venous pulsations present prior to lumbar puncture. There was no correlation between the presence or absence of venous pulsations and blood pressure. Some normal subjects with absent pulsations showed definite pulsations on subsequent examinations. These findings confirm that the presence of spontaneous venous pulsations is a reliable indicator of an intracranial pressure below 180 to 190 mm H2O, while the absence of pulsations may be found with normal intracranial pressure and is therefore not a reliable guide to raised intracranial pressure.