Four were killed in one explosion and a fifth died in what officials called an "insurgent attack," both Friday, the Los Angeles Times reported.
Officials said an improvised explosive device killed three soldiers Thursday in the south.
NATO's International Security Assistance Force didn't reveal the nationalities of the troops but the majority of those serving in southern Afghanistan are U.S. or British, the Times said.
Southern Afghanistan includes the unstable provinces of Helmand and Kandahar, which are Taliban strongholds.
U.S. commanders have said they expect the focus this year to be on eastern Afghanistan along the country's border with Pakistan, the Times said. The dangerous insurgent Haqqani network operates primarily in the east.