The arrests were made in two separate incidents and involved local people, police said.
Two persons were arrested at Gumba Bridge on the outskirts of the capital Kathmandu and 25 kilogrammes of hashish was recovered from them, police said.
The duo aged 25 and 24 years from Dhading district were currently staying at Tarkeshwor Municipality near Kathmandu, they said.
The illegal drug was found hidden inside a car during a security check, police said.
In another incident, three persons were arrested near here with a large quantity of narcotic drugs including spasmo and phenergan, police added.