ObjectiveTo investigate the hypothesis that HIV can be transmitted via contamination of multidose vials of local anaesthetic solution through reuse of needles and syringes.Design and settingLaboratory study. (1) By experiments with multidose vials and disposable needles and syringes, we identified a sequence of events in which HIV could contaminate the anaesthetic solution. (2) Three anaesthetic solutions were contaminated with a laboratory strain of HIV and tested by viral culture and p24 enzyme immunoassay one, two and four hours later to see how long the virus remained active.Results(1) Needles and syringes retained small volumes of fluid after use (mean, 25 μL; in syringe alone, mean 16 μL) which could be transferred to multidose vials of local anaesthetic. (2) 10 mL of anaesthetic solution contaminated with 8 μL of HIV‐infected solution (equivalent to 1% infected lymphocytesin vivo) contained active virus one hour later. In some settings, HIV could be isolated four hours after exposure.ConclusionWhen inadvertently contaminated with HIV, multidose solutions represent a potential source of transmissible virus.