Negative attitudes toward Attention Deficit Hyperactivity Disorder (ADHD) can lead to delays in help-seeking, negative self-image, social isolation, social rejection, and treatment barriers. The aim of the current research was to extend the research literature on ADHD by using a measure of implicit cognition to complement existing questionnaire/self-report data. Study 1 used a behavioural implicit measure known as the Implicit Relational Assessment Procedure (IRAP) and three explicit measures to investigate stigmatising attitudes towards pupils with ADHD. Participants were mainstream primary school teachers (n=16) and trainee primary school teachers (n=14). Overall, statistical analysis of IRAP data showed participants’ results from Study 1 did not demonstrate negative relational bias toward ADHD pupils for teachers or trainee teachers (e.g., participants did not respond faster in affirming typically-developing/positive relations compared to ADHD/positive relations). Correlational tests using Pearson’s r were implemented to determine if there were any implicit-explicit associations demonstrated; results showed two statistically significant effects i.e. typically-developing/positive trial-type correlated with the emotional exhaustion subscale on Maslach Burn-Out Inventory-Educator’s Survey (MBI-ES) for the qualified teacher group and typically-developing/negative trial-type correlated with the stress subscale on the Depression Anxiety Stress Scale (DASS) for the trainee teacher group. Study 2 was a partial replication of Study 1 with a convenience sample of adults (n=41). The rationale was that there was no implicit stigma shown in Study 1 because the participants were highly qualified and familiar with individuals with ADHD and thus failed to show the expected relational bias. The IRAP was used as before and results showed a pro-typically-developing relational bias however, combined pro-ADHD and anti-ADHD relational biases in the ADHD trial-blocks. Results are discussed with regard to further implicit investigation in the area.