United States House of Representatives elections, 1866 Ohio Ohio

| District | Incumbent | Party | First_elected | Result_ |
|---|---|---|---|---|
| Ohio 12 | William E. Finck | Democratic | 1862 | Retired Democratic hold |
| Ohio 13 | Columbus Delano | Republican | 1864 | Lost Re-election Democratic gain |
| Ohio 14 | Martin Welker | Republican | 1864 | Re-elected |
| Ohio 15 | Tobias A. Plants | Republican | 1864 | Re-elected |
| Ohio 16 | John Bingham | Republican | 1864 | Re-elected |
| Ohio 17 | Ephraim R. Eckley | Republican | 1862 | Re-elected |
| Ohio 18 | Rufus P. Spalding | Republican | 1862 | Re-elected |
| Ohio 19 | James A. Garfield | Republican | 1862 | Re-elected |