Outage probability is an important performance measure of wireless communication systems operating in a fading environment. In this paper, we study the outage probability of low-density parity-check (LDPC) coded systems for slow fading channels (nonergodic channels) under the assumption that the transmitter knows only the channel statistics while the receiver has perfect or imperfect channel side information (CSI). The fading coefficient is assumed to be random but stays constant over a LDPC codeword. We define the outage event as the set of channel realizations which disables successful decoding. Based on a density evolution algorithm and stability condition, closed- form outage probabilities are derived for both Rayleigh and Rician fading channels. The effect of channel estimation error on the outage probability is also investigated assuming Gaussian estimation error.