  In this paper, we define what is called a quasi-Reinhardt domain and study
biholomorphisms between such domains. We show that all biholomorphisms between
two bounded quasi-Reinhardt domains fixing the origin are polynomial mappings,
and we give a uniform upper bound for the degree of such polynomial mappings.
In particular, we generalize the classical Cartan's linearity theorem for
circular domains to quasi-Reinhardt domains.
