Since the advent of antiretroviral treatment against HIV, their use as post-exposure prophylaxis, in health care workers as well as after non professional exposures, is still increasing. Although their efficacy is well documented in selected indications, one should always keep in mind that in most exposures, the risk of side effects and the cost of such an intervention is probably much higher than the low probability of HIV transmission. By balancing the risks and the potential benefits of post-exposure prophylaxis against HIV after a given exposure, if needed with help from a specialist, overprescription can in this way be avoided. The patient's fear about having contracted HIV should finally not drive one to forget the risk of transmission of other communicable disease, like viral hepatitis, tetanus and STD.