Between February 1977 and May 1978, phleborheograms were done on 328 extremities. Interpretable tracings were obtained in 322 (98.2%). Results were positive for 102 extremities, negative for 220 extremities, and equivocal or uninterpretable for six extremities. Phlebograms as well as phleborheograms were done in 64 extremities. Phlebograms were positive in 41 and negative in 23. The overall agreement between the interpretations of the phlebograms and phleborheograms was 95.3%. The phleborheogram was positive in each case in which the phlebogram was positive. In three cases with negative phlebograms the phleborheogram was positive. Thus, the sensitivity was 100%, and the specificity was 87%. Phleborheography is a useful adjunct to the diagnosis of venous obstruction. It has a high degree of sensitivity (100% in our experience). Clinical correlation is necessary to determine the most likely cause of venous obstruction in individual cases.