Lentiviral gene vectors are an important tool in gene therapy and basic biomedical research. They are transducing viral particles, normally replication defective, which are generated using the packaging machinery of lentiviruses. These vectors are used to deliver the encapsidated payload genes to the nuclei of the target cells, offering stable transgene expression in many settings in vitro and in vivo. Successful generation of high-titre lentiviral vectors capable of efficiently expressing transgenes over long period of time is governed by a number of vector design rules, some of which are common to all gene vectors while others are specific to lentiviral vectors. Construction of lentiviral vectors with the cargo genes driven by tissue-specific promoters is a particular challenge. This review focuses both on the guiding principles and the technical know-how of the lentiviral gene vector design.