Stroke produces brain damages that results in sensory, motor, and cognitive impairments which reduce the patient's quality of life and social participation. Upper limb recovery is a complex process whose goal is to allow the patients to gain, in part or completely, independence in daily living activities, for that it represents one of the most important rehabilitation focus. Virtual reality is a fairly recent approach able to simulate concrete movements and functional tasks in a higher dosage compared to other therapies. It seems that the use of VR could improve limb function, however, the amount of this gain is still unclear because of insufficient evidence. This study aims at quantitatively investigating the effectiveness of an HMD immersive virtual reality system on the upper limb functioning in subacute stroke survivors.