In summary, the c.804‐7C>A, c.‐1668T>A, c.803+221C>A and c.‐173A>T polymorphisms of the TPH1 gene and the c.‐1449C>A, c.‐844G>T polymorphism of the TPH2 gene may be associated with depression in the Polish population. Here, TPH2 is linked to depressive disorder.