It is the fourth week at No. 1 for Gonzaga (28-0), the only unbeaten team in Division I. The Zags received 59 first-place votes from the 65-member national media panel on Monday.
Villanova (26-2) received five first-place votes. Kansas (24-3), which beat West Virginia and Baylor last week, got the other No. 1 vote.
Three teams from the Pac-12 -- Arizona, UCLA and Oregon -- are fourth through sixth. Louisville is seventh, followed by North Carolina, Baylor and Duke.
Baylor, which lost to Texas Tech and Kansas, dropped five places from fourth.
Wichita State makes its first Top 25 appearance since last season. The Shockers replace South Carolina, which fell out after a five-week run in the poll.
Kentucky moved up two spots to 11th and is followed by West Virginia, Florida, Purdue, Cincinnati, Wisconsin, SMU, Virginia, Florida State and Saint Mary's.
The last five ranked teams are Notre Dame, Butler, Creighton, Maryland and Wichita State.
The Shockers (25-4), who were ranked for six weeks last season, enter the poll on a 10-game winning streak, and they are tied with Illinois State at 15-1 for first place in the Missouri Valley Conference.
South Carolina (20-7) dropped out from 21st after losing to Arkansas and Vanderbilt last week.
Two top-10 matchups highlight the week's double-ranked games.
On Wednesday, No. 7 Louisville is at No. 8 North Carolina, and on Saturday, No. 5 UCLA is at No. 4 Arizona.
Second-ranked Villanova has two games against ranked teams this week, hosting No. 22 Butler on Wednesday and No. 23 Creighton on Saturday.
The other game featuring two ranked teams is No. 13 Florida at No. 11 Kentucky on Saturday.