The prevalence of attention deficit hyperactivity disorder (ADHD) is 9.8 % in U.S. children. Several variants of Latrophiln-3 (LPHN-3) are associated with ADHD. Using CRISPR/Cas9 we deleted exon 3 in rats to create a global Lphn3 knockout. These rats are hyperactive, startle hyper-reactive, impulsive, and have impaired working, spatial, and egocentric learning and memory. Deltamethrin (DLM) is a widely used pyrethroid insecticide. Several epidemiological studies report an increase in ADHD prevalence in children exposed to pyrethroids. Developmental exposure to DLM in rats results in multiple behavioral deficits. The present experiment tested whether Lphn3 disruption interacts with developmental DLM exposure. Because Lphn3