Symptoms of parental stress can be perceived in families of children with mental health disorders, such as attention-deficit/hyperactivity disorder (ADHD). This research investigated the presence of stress in parents of children with and without ADHD and verified the possible association of these levels with inattention and patterns of children's hyperactivity/impulsivity. The participants were 78 parents with children between 8 and 12 years old with ADHD (experimental group) and without ADHD (control group). The study was conducted in two public schools, at a university hospital and in the participant's homes. Sociodemographic questionnaires, the Parenting Stress Index (PSI) and the Multimodal Treatment Study of Children with Attention-Deficit Hyperactivity Disorder questionnaire (MTA-SNAP IV), were used in this research. Relative frequency statistics and factor, correspondence and variance analysis were used for data analysis. The main results were the highest stress level (68.19) in parents of children without ADHD compared with that for parents of children with ADHD (27.37). The parents in the experimental group observed more behaviours of the child characteristics of ADHD (distraction, hyperactivity and impulsivity) than did the parents in the control group, with important differences identified between the two groups. This finding shows that although the parents of children with ADHD report more characteristics of inattention, hyperactivity and impulsivity, their stress level is lower when compared with the control group.