The main goal of the present study was to examine the effect of Structural Family Therapy (SFT) based psychoeducation program on family functionality in families of children with attention deficit hyperactivity disorder (ADHD). This study was an experimental study based on the pre-test, post-test, and follow-up test model, with experimental and control groups. Family functionality, which was the dependent variable of the study, was measured with the Mc Master Family Assessment Device (FAD). The independent variable of the research was the psychoeducation program applied only to the experimental group. The research consisted of parents who have children between 7-10 years of age diagnosed with ADHD. A 10-week psychoeducation program developed by the researcher based on SFT was offered to the experimental group. Mann-Whitney U and Wilcoxon Signed-Rank tests were used in the analysis of the data. The results obtained from the study found out a significant difference (p<.05) between the post-test scores of the control and experimental group. Additionally, a significant difference (p<.05) was found between the FAD scores of the parents in the experimental group before and after the experiment. The results showed that the SFT based psychoeducation program applied to parents was effective in increasing family functionality.