A grenade attack in the southern town of Samawa claimed the first Dutch fatality of the occupation.
According to the Radio Netherlands website on Tuesday, the soldier was killed as he was crossing the bridge over the Euphrates.
The second was seriously injured, while two more received only shrapnel wounds to the legs.
About 1250 Dutch soldiers are based near the town, where Japanese troops are also stationed.
A US soldier was also killed and another wounded in a roadside bomb attack near Samarra, north of the Iraqi capital.
Part of the 1st Infantry Division, the marine was killed as he searched a main road for booby traps.
Another US soldier was killed in the centre of the northern Iraqi city of Mosul on Monday, a US army spokesman said.
Colonel Joseph Piek confirmed the soldier died while on patrol at about 19:30pm local time (1530 GMT) on Monday.
ِِِAttacks in the last 24 hours have raised the US-led occupation force's toll to 881, of which 772 are American fatalities.