Brain–machine interfaces have the potential to restore some normal motor function in paralysed individuals. The authors implanted a 96-channel microelectrode array into the motor cortex of an individual with tetraplegia and connected it to a prosthetic limb. After 3 months of training, the individual could carry out skilful and co-ordinated upper-limb motor tasks. This represents an important advance in the development of neuroprosthetic limbs that use a patient's natural command signals to guide movement.