Differential diagnosis between Vegetative State and Minimally Conscious State is a challenging task that requires specific assessment scales, involvement of expert neuropsychologists or physicians and use of tailored stimuli for eliciting behavioural responses. Although misdiagnosis rate as high as 40% has been reported, no clear guidelines are available in literature on the optimal setting for assessment. The present study aims to analyse score differences in behavioural assessments of persons with disorders of consciousness (DOC) with or without family members and to determine whether the presence of caregivers could improve clinical accuracy in diagnostic evaluation. The research was conducted on 92 adults with DOC among 153 consecutive patients enrolled in the Coma Research Centre of the Neurological Institute C. Besta of Milan between January 2011 and May 2013. The results indicate that in almost half of the sample the scoring, thus the performance, observed with caregivers was better than without them. Furthermore, in 16% of the sample, when assessment was performed with caregivers there was a change in diagnosis, from Vegetative to Minimally Conscious State or from that to Severe Disability. Finally, statistical differences were found in relation to diagnosis between mean scores in the "visual function" Coma Recovery Scale revised's subscale obtained by raters plus caregiver and rates only assessment. This study demonstrates how the presence of caregivers can positively affect behavioural assessments of persons with DOC, thus contributing to the definition of the optimal setting for behavioural evaluation of patients, to decrease misdiagnosis rates.