This chapter discusses genome-wide association studies (GWAS) in narcolepsy, which aimed to identify additional gene variants that contribute to its pathogenesis in Asian and Caucasian populations. The published GWAS in narcolepsy have indeed uncovered new genes outside the human leukocyte antigen (HLA) region that confer risk for developing narcolepsy. Taking into account all published GWAS, the multi-ethnic T-cell receptor alpha (TCRA) association is the most reliable and stable genetic association found to date apart from the known HLA association. The identification of common variants in immune-related genes with small to modest effect sizes in narcolepsy is in line with most of the published GWAS in other diseases. In narcolepsy, however, it seems unlikely that variants outside the HLA region will contribute with similar or stronger effects than the known HLA association.