Abstract Recent development of near infrared light therapy (NILT) as an acute stroke treatment is promising. In various preclinical animal stroke models, NILT has been shown to be effective in improving long-term stroke outcome. More importantly, NILT has a long postischemic therapeutic window that has not been previously observed in other treatment modalities. The preliminary efficacy and safety of NILT in acute stroke patients were demonstrated in the recently published phase II NeuroThera Effectiveness and Safety Trial (NEST-1). If confirmed by the NEST-II trial, NILT will revolutionize acute stroke management as ut has a long time window (possible 24 hr) for therapy. Moreover, understanding the mechanisms of action of NILT will provide a new therapeutic target for future drug or device development.