Abstract Background'Slamming' refers to injecting drugs, particularly methamphetamine, GHB/GBL or mephedrone, before or during sex among men who have sex with men (MSM), and is associated with risky injecting and sexual practises. We examined the impact of 'slamming' on HIV-related risk among people who inject drugs (PWID).MethodData from a repeated voluntary unlinked-anonymous survey of PWID in the UK (excluding Scotland) were analysed. Drug use, injecting and sexual risk and HIV prevalence among men are described.ResultsBetween 2000/01-2014/15 the proportion MSM increased among all male PWID (4.4% to 8.4%; p<0.001) and recent initiates to injecting (6.9% to 12%; p<0.001). Stimulant injection increased among MSM (57% to 77%; p<0.001). HIV prevalence increased (2.2% to 8.3%; p=0.2) among MSM, despite remaining stable among other men. In 2013-2015, compared to other men (n=3497), being MSM (n=323) was associated with recent initiation (8% vs 13%, p=0.004), injecting mephedrone and ketamine (6.4% vs 12%, 3.8% vs 9.3% p<0.001), sharing needles/syringes ( 11% vs 15%; p=0.07) and more sexual partners (10+: 4.1% vs 31%, p<0.001). Recent initiates (n=42) reported more mephedrone and ketamine injection than other MSM (44% vs 12%, p<0.001, 26% vs 10%, p=0.009), lower condom use (always: 36% vs 51%, p=0.072) and more sexual partners (10+: 33% vs 24%, p=0.168).ConclusionAn increasing proportion of male PWID are MSM. HIV prevalence is increasing in this group. Data suggests that injecting 'slamming' drugs is becoming more common among MSM PWID, particularly among recent initiates. Targeted harm reduction and sexual health interventions are required.