The V-BLAST structure is a promising MIMO transmission scheme that attempts to utilize the high capacity of a MIMO system while maintaining low complexity. While no channel knowledge is required at the transmitter, accurate estimates of the channel are necessary at the receiver. The performance of V-BLAST under channel estimation errors is analyzed in this paper and a very tight error floor is derived. This error floor is due to the equivalent system noise which is a combination of the channel estimation errors and the additive white Gaussian receiver noise.