| Conventional Long Name: | Ilocos |
| Common Name: | Ilocos |
| Nation: | Philippines |
| Status Text: | Province of the Philippines |
| Era: | Colonial Period |
| Year Start: | 1571 |
| Year End: | 1818 |
| Date End: | February 2 |
| S1: | Ilocos Norte |
| Flag S1: | Flag of Spain (1785–1873, 1875–1931).svg |
| S2: | Ilocos Sur |
| Flag S2: | Flag of Spain (1785–1873, 1875–1931).svg |
| Image Map Caption: | Location of the historical province of Ilocos. |
| Capital: | Vigan |
| Today: | Abra Ilocos Norte Ilocos Sur La Union |
Ilocos was a province in northern Luzon, Philippines that comprised the present-day provinces of Ilocos Norte, Ilocos Sur, parts of La Union, and Abra.[1] On February 2, 1818, the province was split into Ilocos Norte and Ilocos Sur by the promulgation of a royal decree[2] due to rapid population growth.[3]