BACKGROUND: We report on an exploratory qualitative study investigating drug injectors' narratives of vein damage and groin (femoral vein) injection associated with the injection of crack-heroin speedball. METHODS: We undertook 44 in-depth qualitative interviews among injectors of crack-heroin speedball in Bristol and London, England, in 2006. FINDINGS: The data suggest an emerging culture of crack-based speedball injection. Injectors' narratives link speedball injection with shifts towards groin injection articulated as an acceptable risk, and not merely as a last resort in the face of increased vein deterioration associated with speedball. Accounts of vein damage linked to speedball emphasize 'missed hits' related to the local anaesthetic action of crack, the excess use of citric in the preparation of speedball injections and 'flushing' when making a hit. We find that groin injection persists despite an awareness of health risks and medical complications. CONCLUSIONS: We emphasize an urgent need for reviewing harm reduction in relation to vein care in the context of shifts to crack-based speedball injection, and the use of the femoral vein, among UK injectors. There is an additional need for interventions to promote safer groin and speedball injecting as well as to prevent transitions toward groin and crack injection.