3-Methylhypoxanthine has been reacted with various alkyl halides under basic conditions. Allylic and benzylic halides reacted mostly at N-7 to give dialkylated purines, however, ring-opened imidazole by-products, probably resulting from N-1 alkylation and hydrolysis of the formed salt, were often obtained in minor amounts. Less reactive halides required a larger excess, higher temperatures, and longer