Autism spectrum disorder (ASD) is a pervasive and lifelong developmental disorder that currently affects 1 in 54 children. Individuals with autism are often severely impaired in communication, social skills, and cognitive functions. Particularly detrimental characteristics typical of ASD include the inability to relate to people and the display of repetitive stereotyped behaviors and uncontrollable temper outbursts over trivial changes in the environment, which often cause emotional stress for the children, their families, schools and neighborhood communities. To date, there is no cure for ASD, and the disorder remains a highly disabling condition. Recently, transcranial direct current stimulation (tDCS), a noninvasive neuromodulation technique, has shown great promise as an effective and cost-effective tool for reducing core symptoms, such as anxiety, aggression, impulsivity, and poor social communication, in patients with autism. Although the empirical findings in patients with ASD are encouraging, it remains to be determined whether these experimental data can be translated into real-world benefits. An important next step is to better understand the factors affecting the long-term efficacy of tDCS treatment - in particular, the possible risk factors associated with relapse in patients with ASD and the role of booster session tDCS as an add-on treatment to induce long-lasting neuroplastic effects in ASD.