Forty patients with atypical, chronically swollen, painful lower extremities were observed from two to ten years. Most patients had had previous diagnoses of lymphostasis or venostasis. Clinical reevaluation indicated lipedema (painful fat syndrome) as described by Allen and Hines in 1940 and not reported on since. Fourteen patients were selected at random for detailed pathologic and chemical (tissue and serum) examinations as well as flow studies in the lymphatic, venous, and arterial systems. All study results were essentially normal except for chemical examinations. Significant amounts of lipids containing an altered fatty acid pattern were found in plasma and tissue examined by biopsy. (JAMA228:1656-1659, 1974)