BACKGROUND Washington State was one of the first states to legalize recreational marijuana. Increased availability of marijuana may result in more unintentional pediatric exposure, which often presents as altered mental status with unknown cause. OBJECTIVE To quantify unintentional pediatric marijuana exposures reported to the Washington Poison Center (WAPC) prior to and after legalization and commercial availability of recreational marijuana. METHODS Data were obtained from the WAPC database, toxiCALL®. Patients ≤ 9 years old with a reported marijuana exposure between July 2010 and July 2016 were included in the analysis. Patient and exposure characteristics were summarized and median exposure frequencies were calculated for the periods prior to and after legalization. RESULTS There were 161 cases meeting the inclusion criteria that occurred between July 2010 and July 2016. Of these, 130 (81%) occurred in the 2.5-year period after legalization of recreational marijuana in January 2013. The median age of exposed children was 2 years (range 0-9 years). Eighty-one percent of the exposures occurred in the child's own home. The number of exposures per month increased after recreational marijuana was legalized in November 2012, and increased further once recreational marijuana shops were legally allowed to open in July 2014. CONCLUSIONS Reported unintentional pediatric marijuana exposure has increased in the state of Washington since recreational marijuana was legalized. As marijuana becomes more available, clinicians should be aware of the risk of unintentional pediatric marijuana exposure, and this should inform lawmakers regarding regulations around childhood exposure to marijuana.