| Country: | Wales |
| Welsh Name: | Ynysmaerdy |
| Static Image: | Ynysmaerdy Terrace, Ynysmaerdy 2016.JPG |
| Constituency Welsh Assembly: | Ogmore |
| Official Name: | Ynysmaerdy |
| Unitary Wales: | Rhondda Cynon Taf |
| Lieutenancy Wales: | Mid Glamorgan |
| Constituency Westminster: | Ogmore |
| Post Town: | Pontyclun |
| Postcode District: | CF72 |
| Postcode Area: | CF |
| Dial Code: | 01443 |
| Coordinates: | 51.5498°N -3.3952°W |
| Os Grid Reference: | ST033843 |
Ynysmaerdy is a village near Talbot Green and Llantrisant in Rhondda Cynon Taf, Wales. Even though there is no direct access to the village of Llanharan, due to older parish boundaries it falls under the community of Llanharan.[1] It is home to the Royal Glamorgan Hospital.