Thirty-year-old Somati Chepang and her two sons - Man Bahadur, 9 and Santa Kumar, 6 - who fell sick after consuming poisonous mushroom four days ago died in course of treatment at the Bharatpur Hospital.
Somati's husband Buddhi Bahadur Chepang, 35 and son Arjun, 18 are undergoing treatment at the hospital.
Family belongs to a tribal group called Chepang residing in Kabilas village of Chitawan district.
The Chepang people in the remote areas of Chitwan eat wild fruits and vegetables due to acute shortage of food stuffs.
Two years ago, eight people of a same family had died after consuming the wild mushroom at Lothar village in the same district.