| Mahadewa Portaha | |
| Native Name: | महादेवा पोर्ताहा |
| Settlement Type: | Village development committee |
| Pushpin Map: | Nepal |
| Pushpin Label Position: | bottom |
| Pushpin Mapsize: | 300 |
| Pushpin Map Caption: | Location in Nepal |
| Subdivision Type: | Country |
| Subdivision Name: |  Nepal |
| Subdivision Type1: | Zone |
| Subdivision Name1: | Sagarmatha Zone |
| Subdivision Type2: | District |
| Subdivision Name2: | Siraha District |
| Population As Of: | 1991 |
| Population Total: | 3050 |
| Population Density Km2: | auto |
| Population Blank1 Title: | Ethnicities |
| Timezone: | Nepal Time |
| Utc Offset: | +5:45 |
| Coordinates: | 26.65°N 86.47°W |
Mahadewa Portaha is a village development committee in Siraha District in the Sagarmatha Zone of south-eastern Nepal; the population is 6,977 people.[1]