Lithium is a drug of choice as a mood-stabilizer for the maintenance treatment of bipolar disorder. The prophylactic efficacy of lithium can be determined by genetic factors, partially related to a predisposition to bipolar disorder. In the field of psychiatric genetics, the first decade of the 21st century was dominated by the “candidate gene” research. In this paper, the studies on candidate genes connected with lithium prophylaxis performed at the Poznań University of Medical Sciences in 2005-2018 are presented. During this time, the polymorphisms of multiple genes have been investigated, many of which are also connected with a predisposition to bipolar illness. The associations with lithium prophylactic efficacy were found for the polymorphisms in 5HTT, ACP1, ARNTL, BDNF, COMT, DRD1, FKBP5, FYN, GLCC, NR3C1, and TIM, genes, but not those in 5HT2A, 5HT2C, DRD2, DRD3, DRD4, GRIN2B, GSK-3β, MMP-9, and NTRK2 genes. The polymorphism of the GSK-3β gene was found to be associated with the kidney side-effects occurring during lithium therapy. Possible roles for these genes in both the mechanism of lithium prophylactic activity and pathogenesis of bipolar mood disorder were discussed.