•Analysis of pre-treatment resistance-associated substitutions (RASs) among recently HCV-infected MSM with risky behaviours.•Uncommon NS3/NS5A RASs among recently HCV-infected MSM with risky behaviour.•High prevalence of subtype-specific polymorphisms in GT4d infections.•Reassurance of the clinical management of HCV infection in this population. Presence of baseline hepatitis C virus (HCV) resistance-associated substitutions (RASs) can impair treatment outcome of direct-acting antivirals. We investigated the prevalence of pre-treatment HCV resistance among recently HCV-infected men who have sex with men (MSM) with high risk behaviours, either human immunodeficiency virus (HIV) co-infected or at high risk of HIV acquisition and under pre-exposure prophylaxis (PrEP). NS5A and NS3 fragments were deep sequenced on pre-treatment samples of 72 subjects using Illumina MiSeq paired-end sequencing technology. Ultra-deep sequencing data were analysed by SmartGene® platform. RASs mentioned in the literature were analysed and interpreted depending on genotype (GT) at 10% cut-off. HCV genotyping showed 36 (50.0%) GT1a, 31 (43.1%) GT4d and 5 (6.9%) GT3a infections. Fifty-five patients (76.4%) were co-infected with HIV and 15 (20.8%) received PrEP. In GT1a viruses, NS3 RASs were found in 4/30 viruses (13.3%; S122 G/N, R155 K and I170 V) and Q80 K polymorphism was present in 14/30 viruses (46.7%). No NS3 RASs were detected in GT4d and GT3a viruses. NS5A RASs were detected in 3/36 GT1a viruses (8.3%; Q30E/R, L31 M and H58 L). NS5A subtype-specific polymorphisms L30R and T58 P were found at high frequencies in 31/31 (100%) and 16/31 (51.6%) GT4d viruses, respectively. One RAS M31 L was also observed along with the polymorphisms L30R and T58 P. No NS5A RASs were detected in GT3a viruses. A low level of RASs to NS3 and NS5A inhibitors in pre-treatment samples was detected in the study population. Our findings reassure the clinical management of HCV infection in this high-risk population.