=================================== Title: Probabilistic aspects of deterministic Lorentz gas models Abstract In this talk, I will survey some recent results on probabilistic properties of the planar periodic Lorentz gas, which can be viewed as a simple deterministic model for Brownian motion. The two main themes are (a) decay of correlations, namely the rate at which the gas mixes; (b) statistical limit laws such as the central limit theorem, the law of the iterated logarithm, and convergence to Brownian motion. ================================================================