Iowa Highway 16 (Iowa 16) is a state highway running from west to east in southeastern Iowa. The highway has a length of 65.18 miles (104.90 km). The western terminus of Iowa Highway 16 is at an intersection with U.S. Highway 34 between Agency and Batavia. The eastern terminus is located at Wever at an intersection with U.S. Highway 61.

Iowa 16 begins by going south from a freeway interchange with U.S. Highway 34. It goes south to Eldon, then turns southeast on an alignment north of the Des Moines River. Near Douds, it intersects Iowa Highway 98. It continues east until Iowa Highway 1, with which it runs concurrent briefly. It goes east until Houghton, then intersects U.S. Highway 218 and Iowa Highway 27. It continues southeasterly to Wever on an alignment just south of the Skunk River and ends at U.S. Highway 61.

The current version of Iowa Highway 16 is the second occurrence of the route number in the state; the route number first occurred on a highway that was decommissioned in 1930 and ran between the Minnesota and Missouri state lines.