The study of the correlations between occlusive rheoplethysmography (RPO) and phlebography, carried out in 170 explorations, shows an over-all rate of 78.3% correct correlations. This correlations is more accurate for negative RPOs (91.8%) than for positive ones (59.6%). There are in fact few inaccurate negatives (i.e. venous thrombosis with negative RPO) but there are a certain number of erroneous positives, linked basically with states of cardiac insufficiency and phlebitic after-effects. The RPO examination is a useful complement to the clinical data; it means that the number of necessary phlebographical examinations can be cut down, and it provides a useful guide to treatment options.