Last name Портнйагин (Портнйагин 
) , across the world, is an extremely rare cognomen. The last name Портнйагин is habitual in Eastern Europe, particularly Russia, where it is an extremely rare surname.
| VARIANT | COUNTRY |
|---|---|
| Портнйагин | Russia |
Portniagin, Portnjagin, and Portnyagin