This retrospective study of 10 patients with hyperthyroidisma and diabetes mellitus concerned 8 women and 2 men, aged from 15 to 77 years. The two disease developed at the same time in 8 cases. Diabetes mellitus occurred first in 2 cases. Common signs were loss of weight. Hyperthyroidism led to tachycardia at more than 100 bpm. Diarrhea was observed simultaneously in 2 cases and muscular weakness in 5. Goiter was found in 10 cases with a diffuse aspect. Graves' disease was diagnosed with exophthalmia in 9 cases and affected both eyes in 8. Elevated levels of thyroid hormones confirmed diagnosis in 8 cases. Diabetes was insulin-dependent in 3 cases and non-insulin dependent in the 7 others. IDDM patients (2 female and 1 male) were aged 15, 17 and 38. Keto acidosis was the first symptom in all cases. NIDDM patients (6 female and 1 male) were aged between 37 and 77.