The absence of a diagnostic test to determine actual or incipient thromboembolic disease makes an analysis of this condition basically unscientific and subject to much variation. However, the data from over 1,000 cases of thrombophlebitis in 2 general hospitals show much agreement on diagnosis, diagnostic errors, methods of management, and inadequacies of treatment. This is an analysis of the common problems in the diagnosis and treatment of thrombophlebitis, with suggestions for improvement. Material During the past 10 years, there were 608 cases of thrombophlebitis at University Hospital; at Mount Carmel Hospital there have been 409 cases in the past 14 years. These patients were treated by a large number of physicians, many of whom are on the staffs of both hospitals. There were 611 females and 406 males. Age and sex distribution were similar in the 2 hospitals. The age distributions are shown in Figure 1. A similar age range