| Official Name: | Villarcayo de Merindad de Castilla la Vieja |
| Pushpin Map: | Spain |
| Pushpin Map Caption: | Location in Spain |
| Subdivision Name3: | Villarcayo de Merindad de Castilla la Vieja |
| Area Total Km2: | 150 |
| Population Density Km2: | auto |
| Utc Offset: | +1 |
| Utc Offset Dst: | +2 |
| Coordinates: | 42.9391°N -3.5719°W |
Villarcayo de Merindad de Castilla la Vieja (pronounced as /es/) is a municipality located in the province of Burgos, Castile and León, Spain. According to the 2004 census (INE), the municipality has a population of 4,031 inhabitants.