BackgroundRecently, interactive video games (IVGs) have been used as a health-care intervention that provides both exercise and cognitive stimulation. Several studies have shown that IVGs can improve postural control, gait, cognition, and functional independence in elderly people and patients with neurological disease. However, there is a lack of evidence about the effects of IVGs on frail and pre-frail elderly people. The aim of this study was to evaluate the feasibility, safety, and acceptability of playing Nintendo Wii Fit Plus™ (NWFP) interactive video games, and the functional outcomes (postural control, gait, cognition, mood, and fear of falling) in frail and pre-frail older adults. MethodsThis study is a randomized controlled, parallel-group, feasibility trial. Participants were frail and pre-frail older adults randomly assigned to the experimental group (EG, n = 15) or control group (CG, n = 15). Participants in the EG performed 14 training sessions, lasting 50 min each, twice a week. In each training session, participants played five of 10 selected games, with two attempts at each game. Participants in the CG received general advice regarding the importance of physical activity. All participants were assessed on three occasions by a blinded physical therapist: before and after intervention, and 30 days after the end of the intervention (follow-up). We assessed the feasibility (score of participants in the games), acceptability (game satisfaction questionnaire), safety (adverse events during training sessions), and functional outcomes: (1) postural control (Mini-BESTest); (2) gait (Functional Gait Assessment); (3) cognition (Montreal Cognitive Assessment); (4) mood (GDS-15); and (5) fear of falling (FES-I). ResultsParticipants in the EG improved their scores in all 10 games, reported that they understood and enjoyed the tasks of the games, and presented few adverse events during the practice. There was a significant improvement in the Mini-BESTest and Functional Gait Assessment in the EG when compared with the CG (p < 0.05). ConclusionThe use of NWFP was feasible, acceptable, and safe for frail older adults and improved their postural control and gait. There were no effects on cognition, mood, or fear of falling.This trial was registered in the Brazilian Registry of Clinical Trials (RBR-823rst) on 11 June 2016.