| Official Name: | Cynthiana, Ohio |
| Settlement Type: | CDP |
| Mapsize: | 250px |
| Subdivision Type: | Country |
| Subdivision Name: | United States |
| Subdivision Type1: | State |
| Subdivision Name1: | Ohio |
| Subdivision Type2: | County |
| Subdivision Name2: | Pike |
| Subdivision Type3: | Township |
| Subdivision Name3: | Perry |
| Unit Pref: | Imperial |
| Population As Of: | 2020 |
| Population Footnotes: | [1] |
| Population Total: | 57 |
| Population Density Km2: | auto |
| Population Density Sq Mi: | auto |
| Timezone: | Eastern (EST) |
| Utc Offset: | -5 |
| Timezone Dst: | EDT |
| Utc Offset Dst: | -4 |
| Elevation Ft: | 971 |
| Coordinates: | 39.1736°N -83.3483°W |
| Postal Code Type: | ZIP |
| Blank Name: | FIPS code |
| Blank1 Name: | GNIS feature ID |
| Blank1 Info: | 2628880 |
Cynthiana is a census-designated place in northwestern Perry Township, Pike County, Ohio, United States. Cynthiana no longer has a post office and the mailing address has been changed to Bainbridge, OH 45612. It lies along State Route 41. The population was 57 at the 2020 census.