Pfeiffer Lake is an unorganized territory in Saint Louis County, Minnesota, United States. The 2000 census population was three.
According to the United States Census Bureau, the unorganized territory has a total area of 36.3 square miles (94.1 km<sup>2</sup>); 36.2 square miles (93.7 km<sup>2</sup>) is land and 0.2 square mile (0.4 km<sup>2</sup>) (0.47%) is water.
As of the census of 2000, there were three people, two households, and one family residing in the unorganized territory. The population density was 0.1 people per square mile (0/km<sup>2</sup>). There were thirteen housing units at an average density of .
The median income for a household in the unorganized territory was $13,750, and the per capita income for the unorganized territory was $14,033.