—In the next generation mobile communication systems, high-speed and high-quality packet data services are demanded. Hybrid ARQ (HARQ) is known as one of the promising error control techniques for wireless packet transmission. However, in a severe frequency-selective fading channel, the single-carrier (SC) HARQ throughput performance degrades due to intersymbol interference (ISI). In this paper, we consider joint Tomlinson-Harashima precoding (THP) and frequency-domain equalization (FDE) to obtain the frequency-diversity gain while suppressing the residual ISI after FDE. We evaluate, by computer simulation, the SC HARQ throughput performance using joint THP/FDE in a frequency-selective Rayleigh fading channel. Keywords-components; Single-carrier, hybrid ARQ, TomlinsonHarashima precoding, frequency-domain equalization