[Objectives]  Thiacloprid is one of the most widely used neonicotinoid insecticides. Previous studies have shown that sublethal doses of thiacloprid adversely affect the foraging behaviour, navigation and immunocompetence, of honey bees. In this study, the effects of thiacloprid on five major royal jelly protein genes; Mrjp1, Mrjp2, Mrjp3, Mrjp4, and Mrjp5, four immune related antimicrobial peptide genes; Abaecin, Hymenoptaecin, Defensin1 and Apidaecin, and three genes related to memory formation; Pka, Creb, and Nmdar1, were investigated in the honey bee Apis mellifera L.. [Methods]  Bees were chronically exposed to 0.2 mg/L and 2 mg/L thiacloprid over 10 d after which expression levels of the five major royal jelly protein genes in the hypopharyngeal gland, and the immune and memory related genes in the brain, were measured using RT-qPCR. [Results]  Exposure to both 0.2 mg/L and 2 mg/L thiacloprid significantly inhibited the expression of Mrjp1, Mrjp2, Mrjp3, Mrjp4, Mrjp5 and Apidaecin (P<0.05), whereas expression of Abaecin, Hymenoptaecin, Defensin1 and Nmdar1 was only reduced by exposure to 2 mg/L thiacloprid (P<0.05). However, thiacloprid did not affect the expression of Pka and Creb. [Conclusion]  The thiacloprid-induced decrease in Mrjp1, Mrjp2, Mrjp3, Mrjp4, and Mrjp5 expression may reduce hypopharyngeal gland development, whereas the down-regulation of Abaecin, Hymenoptaecin, Defensin1, Apidaecin and Nmdar1 could be implicated in impaired memory and immune system performance. The results of this study suggest a potential molecular mechanism for some of the known negative effects of thiacloprid on honey bees.