Glaucomatous damage develops in certain patients because of elevated episcleral venous pressure (EVP). To measure the EVP in typical clinical settings, a practical and reliable instrument is needed. We have developed such an instrument, the venomanometer, and present tests of its reproducibility. The intraobserver reproducibility was 0.7 mm Hg, and the mean difference between the readings of two observers was 0.7 +/- 1.2 mm Hg. We then used the venomanometer to study the EVP in 122 eyes of 68 normal subjects distributed in seven age groups between 10 and 80 years. The EVP did not vary with age (mean, 7.6 +/- 1.3 mm Hg). This value is compared with those obtained with other instruments.