The five are - Ramnath Thakur, Harivansh, Kahkasha Parveen (all from JD(U)), C P Thakur and R K Sinha (BJP).
All the three JD(U) candidates are new faces of the party to the Upper House of the Parliament.
"They were declared elected unopposed after the time for withdrawal of nominations during the day ended," said Phool Jha, Secretary of Bihar Assembly and Returning Officer for RS polls.
Ramnath Thakur is the son of veteran socialist leader and former Bihar Chief Minister Karpoori Thakur, while Harivansh is a journalist and editor of Hindi daily 'Prabhat Khabar'.
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They have replaced Shivanand Tiwari, bureaucrat-turned- politician N K Singh and Shabir Ali.
BJP's C P Thakur is a former union minister while R K Sinha has his roots in the RSS.
JD(U) has 118 and BJP 91 MLAs in the assembly.