Surveys were conducted at 29 locations in the Lake Superior, Lake Michigan, and Lake Huron drainages to determine if larval sea lamprey, Petromyzon marinus, inhabit lentic waters. A direct-current shocker and a dredge were used to take samples near the mouths of streams that produce sea lampreys. In the Great Lakes proper, 26 larvae were taken from 10 of the 22 areas that were surveyed. In small lakes tributary to the Great Lakes, 113 larvae were taken from 3 of the 7 lakes studied. Nearly all larvae were collected within 1/4 mile of the mouth of a stream containing larvae, usually from silty-sand substrate in areas protected from severe wave action. Aquatic vegetation and bottom-dwelling animals were usually present at locations where larvae were collected.