Oiartzualdea in Basque (Oarsoaldea in Spanish) is a subcomarca of Donostialdea in Gipuzkoa, formed by four municipalities, Errenteria being the main town.
| Basque Name (Official) | Spanish Name[1] | Population 2001 Census[2] | Population 2011 Census[3] | Population 2018 Estimate[4] | |
|---|---|---|---|---|---|
| Rentería | 38,224 | 39,228 | 39,355 | ||
| 5,834 | 6,011 | 6,045 | |||
| Oyarzun | 9,179 | 10,012 | 10,276 | ||
| Pasajes | 15,962 | 15,727 | 16,128 | ||
| Totals | 69,199 | 70,978 | 71,804 |