Using results from multivariate statistical theory, we first derive new expressions of cumulative distribution function (CDF) of the smallest singular value of Ricean fading MIMO channels with arbitrary rank channel means. Then we investigate the corresponding distributions of some special cases, such as independent and identically distributed (i.i.d.) Rayleigh fading and rank-1 Ricean fading MIMO channels. The formulas of smallest eigenvalue of probability density function (PDF) for complex Wishart matrices are also provided. These new statistical results are then applied to the performance analysis of MIMO systems. Finally, numerical results that confirm the theoretical analysis are presented