  Let F=(F_1,...,F_n):C^n --> C^n be any polynomial mapping. By multidegree of
F, denoted mdeg F, we call the sequence of positive integers (deg F_1,...,F_n).
In this paper we addres the following problem: for which sequence (d_1,...,d_n)
there is an automorphism or tame automorphism F:C^n --> C^n with mdeg
F=(d_1,...,d_n}. We proved, among other things, that there is no tame
automorphism F:C^3 --> C^3 with mdeg F=(3,4,5).
