'Block D') is an upper stage used on Soviet and later Russian expendable launch systems, including the N1, Proton-K and Zenit.

The stage first flew in March 1967 while testing the Zond spacecraft as a part of those programs.

The stage uses liquid oxygen (LOX) and kerosene as propellants, and has one single-chamber RD-58 main engine.

It has 5.70 meters length and generates 83.300 kN thrust for 600 seconds burn time.

[7] As of the early 1990s, the ullage rockets discarded just before the final burns by Block DM fourth stages on Proton launches constituted the largest single group of soviet propulsion systems to have suffered disintegrations contributing to space debris.