Objective: The purpose of this study was to investigate how often drugs used to treat migraine and ADHD are prescribed to the same patients to assess, indirectly, the comorbidity of these disorders. Method: We used data from the Norwegian prescription database for 2006, including the total Norwegian population (N = 4,640,219). Results: Antimigraine drugs were prescribed to 81,225 persons (1.75% of the total population), anti-ADHD drugs to 18,481 persons (0.40%), and 284 persons were prescribed both types of drugs. There was a positive and significant association between prescription of antimigraine and anti-ADHD drugs for all age groups between 20 and 50 for both genders, with odds ratios ranging from 1.76 to 2.81. Conclusion: The prescription patterns for these drugs in adult patients indicate a comorbidity between migraine and ADHD. (Contains 3 tables and 2 figures.)