Abstract. This paper provides new cases of the prime number theorem for Beurling's generalized integers. Let N be the distribution of a generalized number system and let π be the distribution of its primes. It is shown that N (x) = ax + O(x/ log γ x) (C), γ > 3/2, where (C) stands for the Cesàro sense, is sufficent for the prime number theorem to hold, π(x) ∼ x/ log x. The Cesàro asymptotic estimate explicitly means thatfor some k ∈ N. Therefore, it includes Beurling's classical condition. We also show that under these conditions the the Möbius function, associated the the generalized number system, has mean value equal to 0. The methods of this article are based on arguments from the theory of asymptotic behavior of Schwartz distributions and a complex tauberian theorem with local pseudo-function boundary behavior as the tauberian hypothesis.