Background: Evidence suggests that Schizophrenia (SCZ), Schizoaffective Disorder (SAD) and Bipolar Disorder (BPD) share genetic risk variants. ZNF804A gene has been associated with these disorders in different populations. The aim was to analyze the rs1344706 SNP and identify common and rare variants in a targeted region of the ZNF804A gene in SCZ, BPD and SAD Mexican patients compared with a control group.Methods: We genotyped the rs1344706 in 228 Mexican patients diagnosed with SCZ, SAD and BPD, and 295 controls. An additional sample of 167 patients and 170 controls was analyzed to identify rare and common variants using the Sanger-sequence analysis of a targeted region of ZNF804A gene. Results: We replicated the association between the rs1344706 and SCZ, SAD and BPD. In the sequence analysis, we did not identify rare variants; however, we identified three common variants: rs3046266, rs1366842 and rs12477430. A comparison of the three identified variants between SCZ, SAD and BPD did not show statistical differences. Conclusions: Our findings support the evidence suggesting that ZNF804A gene is involved in the etiology of SZC, SAD and BPD. Future studies are needed to identify the pleiotropic effect of this gene in psychiatric disorders.