The attack on the military camp near the town of Buinaksk in Daghestan occurred around 1 am local time, media reports here said.
A Lada car packed with explosives rammed into the gate of the field camp of 136th motorised infantry, following which a a communications vehicle and many tents, where soldiers were sleeping, caught fire, Rossiya 24 TV channel reported.
The attack left five people dead and 39 injured, according to the local media. Many of the injured were in serious condition.
A law enforcement source was quoted as saying that the power of the explosive device was equivalent to up to 100 kg of TNT.
Quoting a Defence Ministry spokesman, RIA Novosti said a special commission led by acting Southern Military District commander Maj Gen Alexander Galkin had left for on-the-spot probe.
Servicemen in Buinaksk have repeatedly come under terrorist attacks.
In July this year, servicemen of the 136th brigade came under fire. Three people were killed in that incident.
In recent months, North Caucasus, particularly in Dagestan and its capital Makhachkala, has often witnessed bomb attacks and shootings.