Duobinary partial response (PR) filtered single-carrier frequency-domain multi-access (SC-FDMA) uplink has a potential to achieve higher spectral efficiency (SE) by allowing spectrum overlapping between adjacent users. However, strong multiuser interference (MUI) degrades the bit-error rate (BER) and throughput performances. In this paper, we present two types of frequency-domain MUI cancellation technique for duobinary PR filtered SC-FDMA, which are frequency-domain iterative parallel MUI cancellation (FD-IPMUIC) and frequency-domain iterative successive MUIC (FD-ISMUIC). A series of minimum mean-square error based frequency-domain equalization (MMSE-FDE), FD-MUIC, and soft-decision decoding using soft output Viterbi algorithm (SOVA) is repeated for a sufficient number of times. By using the SOVA, MMSE-FDE weight and MUI replica are updated. Computer simulation results show that both the BER performance and SE can be improved.