A CASE OF thrombotic thrombocytopenic purpura is presented in which the diagnosis was established histologically premortem by random lymph node biopsy and sternal marrow biopsy. Report of Case A 33-year-old Negro man, a common laborer, was admitted to the Orthopedic Service of the McKinney Veterans Administration Hospital on Oct. 26, 1955, complaining of back pain associated with progressive stiffness over a three-year period. Upon admission he appeared to be healthy except for marked limitation of movement of the entire vertebral column and limitation of expansion of the thoracic cage to I/4 in. (0.6 cm.). X-rays confirmed a diagnosis of extensive rheumatoid spondylitis. Upon admission his hemoglobin was 13.5 gm. per 100 cc.; hematocrit 41%; WBC 5150, with 53% neutrophiles, 40% lymphocytes, 6% monocytes, and 1% eosinophiles. The urinalysis revealed normal findings except for 1+ sugar. Serologic tests for syphilis were negative. The fasting blood sugar was 99 mg. per 100