In the deadliest attack, four Task Force Baghdad soldiers died on Monday when their patrol struck the device in Youssifiyah, 20km south of Baghdad, the US military said.
The other explosion hit a patrol near Balad, 80km north of Baghdad, killing two soldiers from the 29th Brigade Combat Team.
The names of the soldiers were withheld pending notification of their relatives.
The deaths raised to 2024 the number of US service members who have died since the Iraq war began in March 2003.
Monday's attacks also increased the death toll for American forces in October to more than 90, making it the deadliest month in 2005 for US troops in Iraq since January, when 107 were killed.