This thesis aimed to investigate the impact of adult attention deficit/hyperactivity disorder (ADHD) on the perception and identification of lexical tones. Eleven participants were asked to listen to and identify four different pitch contours: high to low, high to mid, low to high, and low to mid. Seven of the participants did not have ADHD and four had been formally diagnosed before their participation. Results showed that the ADHD group performed better than the non-ADHD group overall, and that the ADHD group improved in the second half whereas the non-ADHD group did not.