A case of fixed drug eruption (FDE) secondary to foscarnet is reported. This drug has recently become available on a compassionate use basis for treatment of cytomegalovirus (CMV) infection which may cause significant disease in immunosuppressed patients. Foscarnet provides a useful alternative to the only licensed anti-CMV drug currently available, namely ganciclovir (DHPG), as it has a different toxicity profile. In particular, it does not appear to cause bone marrow suppression which is of importance in AIDS patients as many of them are taking concurrent zidovudine.