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We review transport measurements in a normal metal (N) in contact with one or two superconducting (S) islands. From the experiment, we distinguish the Josephson coupling, the mesoscopic fluctuations and the proximity effect. In a loop-shaped N conductor, we observe large h/2e-periodic magnetoresistance oscillations that decay with temperature T with a 1/T power-law. This behaviour is the signature of the long-range coherence of the low-energy electron pairs induced by the Andreev reflection at the S interface. At temperature and voltage below the Thouless energy $\hbar D / L^2$, we observe the re-entrance of the metallic resistance. Experimental results agree with the linearized quasiclassical theory., Comment: 8 pages, 6 included epsf figures, Invited paper at the LT21 Conference, Praha, August 1996. To appear in Czech. J. of Phys. 46, Part S6 (1996)

We report on the first observation of the re-entrance of the metallic resistance in a mesoscopic proximity superconductor. This occurs at low temperature when the coherence length of electron pairs with a thermal energy is larger than the sample size. This regime breaks down when the voltage is increased above the Thouless energy. We find a qualitative agreement between experimental results and the quasiclassical theory including the Usadel equations.