Pericarditis is a common manifestation of adult still's diseases (ASD), observed in 20% to 3% cases. Pericardial tamponade is more seldom, less than ten cases have been reported in the literature. We reported two observations of patients with ASD and pericardial tamponade above a series of 18 patients with ASD, in one case revealed the disease. The first patient was a 32-year-old women and had fever, arthritis, high white blood cell count and developed pericardial tamponade. The evolution was favourable with bolus of methylprednisolone. In the second case, cardiac tamponade occurred several years after the onset of the disease. Surgical drainage was first required (800 ml) because of inefficacity of oral prednisone. A dramatic improvement was observed after bolus of methylprednisolone. In conclusion pericardial tamponade is a seldom but sometimes the first manifestation of ASD and may required in first intention bolus of methylprednisolone.