For a long time, prescription medications have been sold over the internet. However, illegal business practices threaten the proper supply of medications and public health. It is practically impossible to prevent or control cross-border pharmaceutical mail order trade. If preventive protection fails, criminal law becomes more significant. This work connects to the legal discussion about the permissibility of pharmaceutical mail order trade and continues the debate from a criminal law perspective. The focus is on presenting the criminal liability of domestic and foreign operators of online pharmacies. In particular, the applicability and scope of national criminal provisions concerning cross-border pharmaceutical mail order trade are discussed.