#1. Evidence of suprarenal insufficiency has been sought in 174 patients with tuberculosis. Clinical features have been examined and the level of sodium in the blood serum investigated. #2. Serial sections of glands obtained at autopsy showed suprarenal abnormality in eleven patients. • Serum sodium above 315. • • Three autopsies. • • • One positive inoculation for tubercle bacilli. • Serum sodium below 315. • • twenty -two autopsies. • • • Seven positive on inoculation for tubercle bacilli. • Serial sections. • • Two definite tuberculous lesions. • • Pour small tuberculous foci. • • One amyloid degeneration. #3. Suprarenal insufficiency was diagnosed in four patients, two showed tuberculous lesions of the suprarenals, in one there was no evidence of disease in the glands, while the other is untraced. #4. The normal range of sodium has been assessed as 315 to 350 mgms per 100c.cm. of serum. #5. In 114 cases the level of serum sodium was normal. • In 60 cases the level of serum sodium was low. #6. A low serum sodium indicates a bad prognosis. #7. Such suprarenal lesions as were found, occurred with one exception, in Group with low serum sodium. #8. Pigmentation of the skin was present only in the group with a low serum sodium. #9. Cases with pyrexia, sweating, diarrhoea or vomiting did not have of necessity a low serum sodium. #10. There is no proof that serous effusions or purulent discharges can drain away sufficient sodium to account for the low level, nor that they upset the sodium balance. #11. There is no evidence that cases with a low serum sodium had a low enough sodium intake to explain the decreased serum level. #12. Even with a low sodium intake there is an appreciable loss of sodium in the urine. #13. In the presence of a low serum sodium continued excretion of sodium in the urine suggests suprarenal damage, even'with a low intake. #14. In the absence of factors such as severe vomiting or diarrhoea a low serum sodium is suspicious evidence of suprarenal insufficiency.