For high-speed packet access, hybrid automatic repeat request (HARQ) and multi-input multi-output (MIMO) multiplexing are indispensable techniques. Single-carrier (SC) MIMO block transmission using frequency-domain signal detection such as the frequency-domain linear detection based on the minimum mean square error criterion (MMSED) can improve the HARQ throughput performance over the frequency-selective fading channel. However, the performance improvement is limited due to not only an inter-antenna interference (IAI) but also an inter-symbol interference (ISI) resulting from a severe frequency-selective fading. In this paper, we propose to jointly use a training sequence (TS) aided SC block transmission and a near maximum likelihood (ML) block detection using QR decomposition and M-algorithm (QRM-MLBD) for SC-MIMO HARQ. It is shown, by computer simulation, that SC-MIMO using TS aided QRM-MLBD significantly improves the HARQ throughput performance compared to an often used cyclic prefix (CP) inserted SC-MIMO while significantly reducing the computational complexity. It is also shown that proposed TS aided QRM-MLBD achieves a significantly higher throughput than the MMSED particularly when higher level modulation is used.