Twinrix is the only licensed vaccine that provides dual protection against infection with hepatitis A virus (HAV) and hepatitis B virus (HBV). The standard vaccination schedule for Twinrix is 0, 1 and 6 months. However, many high-risk populations, such as injecting drug users (IDUs), do not complete the vaccination series and, thus, do not acquire sufficient immunity against HAV and HBV. Twinrix can be administered using an accelerated vaccination schedule of 0, 7 and 21 days, with a booster recommended at 12 months. This manuscript reviews the available literature on vaccinating IDUs against HAV and HBV. The authors conclude that there is insufficient evidence regarding whether the accelerated Twinrix HAV/HBV vaccination schedule would yield a greater number of IDUs protected against both HAV and HBV.