Within families, co-occurring attention-deficit/hyperactivity disorder (ADHD) in parents and children may be common. The authors evaluated the hypothesis that parental ADHD may lead to a reporting bias of ADHD symptoms in offspring. They combined 2 family case-controlled studies of ADHD using structured interviews. They compared rates of maternal reported ADHD symptoms among 3 groups of ADHD children: no parental ADHD (n = 231), mother with ADHD (n = 63), and father with ADHD (n = 57). With the exception of 1 symptom, the rates of reporting between groups did not differ. There was no evidence that the discrepancy between maternal reports and self-reports of symptoms differed by parental ADHD. Results were similar across child gender or referral status. These results do not support the notion that parental ADHD affects maternal reports of offspring ADHD.