OBJECTIVE: This study examined the effects of a difficult and individually tailored additional cognitive task on postural stability and electromyographic (EMG) activities of the ankle dorsi- and plantar-flexors, in young and older individuals performing postural tasks of varying difficulties. METHODS: Eight young (mean age=24 years) and eight older (74 years) men took part in the investigation. Centre of pressure velocity and surface EMG of ankle joint muscles were both examined during various postural conditions. RESULTS: The main findings suggested that high levels of muscle activity were a characteristic of age-related declines in postural stability. Moreover, during the complex posture, the postural instability, as well as the EMG activity of the ankle joint muscles, was decreased in older adults when the difficult memory task was added. Regarding young participants, the performance in the cognitive task was significantly improved during the complex posture compared to the easy one. CONCLUSIONS: These findings showed that the execution of a second task would make it possible to improve the performance in the original task. SIGNIFICANCE: This pilot study seemed to show that, depending on age, the task of highest priority would be the cognitive one for young adults and the postural one for older people.