Morbid obesity inducing medical pathologies such as hypertension, hypercholesterolaemia or orthopaedic abnormalities is an increasing problem in adolescents. Intragastric balloons have been used, with a varying degree of success, in adults. An intragastric silicone balloon was filled with 500-700 ml physiological serum in five adolescents (11-17 years old) with a morbid obesity (body mass index percentage (BMI %, calculated as a percentage of normal BMI for patient's sex and age, range 148-293%), and was left in place for six months. The balloons were well tolerated. A transient beneficial effect was noted, with a non-significant trend in decrease of the BMI % after 3 months (P = 0.07). However, 3 months later (6 months after the insertion), the BMI % in all five adolescents was significantly higher than before insertion of the balloon (P < 0.05). We observed a failure to lose weight with the help of an intragastric balloon in five selected adolescents. Since the beneficial effect of intragastric balloons in the five adolescents studied was only temporary, these balloons seem not to be indicated in adolescents with morbid obesity.