The reduction of quantum scattering leads to the suppression of shot noise. In the present paper, we analyze the crossover from the quantum transport regime with universal shot noise, to the classical regime where noise vanishes. By making use of the stochastic path integral approach, we find the statistics of transport and the transmission properties of a chaotic cavity as a function of a system parameter controlling the crossover. We identify three different scenarios of the crossover.PACS numbers: 05.45.Mt, 73.50 Td, 74.40.+k Random transfer of charge in electrical conductors leads to time-dependent fluctuations of the current, a phenomenon called shot noise. In recent years, the shot noise has been extensively studied in mesoscopic conductors [1], small degenerate electron systems of a size comparable to the coherence length of electrons. In contrast to the classical shot noise in vacuum tubes, which was explained by Schottky already in 1918 [2], the shot noise in mesoscopic conductors originates from the quantum-mechanical scattering of electrons. Consequently, in a noninteracting mesoscopic conductor biased by the chemical potential difference ∆µ, the average current I = ∆µ n T n [3] (setting electron charge and the Planck constant e = h = 1), the noise power S ≡ I 2 = ∆µ n T n (1 − T n ) at zero temperature [1], and in general the higher cumulants of current I m [4], are determined by the transmission matrixt, namely by the eigenvalues T n , n = 1, . . . , N , oft †t . The current cumulants I m = ∆µN C m can be expressed via the cumulant generating function (CGF) C m = ∂ m H(λ)/∂λ m | λ=0 . In the semiclassical limit, N ≫ 1, the CGF is given by [5]:where ρ(T ) = N −1 n δ(T − T n ) is the transmission eigenvalue distribution. Eq. (1) generalizes the binomial statistics, and together with the inverse formula (12), provides a connection between the full counting statistics (FCS) and the scattering properties of a mesoscopic system to leading order in 1/N .The quantum origin of shot noise in mesoscopic conductors implies that regardless of the character of disorder, current can flow without noise if quantum scattering is suppressed [6]. Therefore, in the classical limit the noise should vanish even in a chaotic system, such as a mesoscopic cavity, where the transport in quantum regime is universally described by Random Matrix Theory (RMT) [7]. It has been predicted [8] that in a mesoscopic cavity with long-range disorder that models chaotic dynamics the noise power shows an exponential crossover S = S RMT exp(−τ E /τ D ) as a function of the ratio of the Ehrenfest (diffraction) time τ E to the average dwell time of electrons τ D . Ref. [9] suggested that this crossover results from a sharp cut-off introduced by the Ehrenfest time in the exponential distribution P(t) = τ −1 D exp(−t/τ D ) of the dwell times of classical trajectories. Recent numerical analysis [10] has demonstrated that the cut-off leads to a complete separation of the cavity's phase space into the quantum universal part of relative volume ...