This paper deals with performance analysis of a cooperative multiple-input–multiple-output (MIMO) network with spatial multiplexing, wherein multiple half-duplex relays perform noncoherent (i.e., without channel state information) amplify-and-forward (AF) relaying, and the destination employs a linear zero-forcing equalizer. The correlation among the noise samples at the destination, the non-Gaussian nature of the dual-hop channel, and the fact that the relays are located in different positions significantly complicates the performance analysis of the system. In the high-signal-to-noise-ratio (SNR) regime, we derive a simple and accurate approximation of the symbol error probability (SEP) at the destination. In the special case of a relaying cluster, such a result allows discussion of the best placement of the relays and the performance gain of cooperation over the direct (i.e., without relaying) transmission. The theoretical analysis is validated by comparison with semianalytical Monte Carlo simulations.