| San Mateo Nejapam | |
| Settlement Type: | Municipality and town |
| Pushpin Map: | Mexico |
| Pushpin Label Position: | above |
| Pushpin Map Caption: | Location in Mexico |
| Subdivision Type: | Country |
| Subdivision Name: |  Mexico |
| Subdivision Type1: | State |
| Subdivision Name1: | Oaxaca |
| Subdivision Name2: | Página web de San Mateo Nejapam |
| Area Total Km2: | 28.07 |
| Population As Of: | 2005 |
| Population Total: | 1127 |
| Timezone: | Central Standard Time |
| Utc Offset: | -6 |
| Timezone Dst: | Central Daylight Time |
| Utc Offset Dst: | -5 |
| Coordinates: | 17.65°N -123°W |
San Mateo Nejapam is a town and municipality in Oaxaca in south-western Mexico. The municipality covers an area of 28.07 km2. It is part of the Silacayoapam District in the Mixteca Region.
As of 2005, the municipality had a total population of 1,127.[1]