There are many parts of Nepal into which the entry of foreigners is strictly controlled. Many treks that may be suggested on a map are in restricted areas and you either cannot get a permit for those regions or must travel with a liaison officer and pay for a special permit. Some areas specifically closed to foreigners are: Walunchung Gola, Rolwaling and the route to Nangpa La in Khumbu. When planning your trek, assume that these areas will remain closed. Don't count on a last-minute change in the rules. Police checkposts are numerous in the hills and police will turn you back if you try to trek into a restricted area.

Officially there are no longer any restricted areas in Nepal. The immigration office rules now state that "trekkers are not allowed to trek in the notified areas previously known as restricted". Rather than get involved in all this semantic complication, the term "restricted" is used here to refer to places that are closed to trekkers, or open to trekkers only when accompanied by a policeman (a liaison or "environmental" officer).