School teachers play an important role in the identification and assessment of pupils' difficulties, and have been considered one of the most valuable sources of information with regard to attention deficit hyperactivity disorder (ADHD) diagnoses. The study examines and compares general and special education teachers' knowledge and misconceptions about ADHD. In addition, it seeks to investigate the role of specific demographic variables, such as teaching experience and level of exposure to ADHD, on teacher knowledge. Two hundred thirty-four primary school teachers from 20 public school of the area of Athens, Greece completed the ADHD Knowledge Based Questionnaire. Findings suggested that special education teachers are more knowledgeable of issues related to ADHD in comparison to general education teachers. Both general and special educators were found to be most knowledgeable of the definition and characteristics of ADHD and least knowledgeable of its etiology and treatment. These findings support previous empirical evidence highlighting the need of providing teachers with continuous training and support to be better equipped in meeting the needs of ADHD pupils in mainstream school settings.