A theta flux distortion was a type of astronomical distortion that Starfleet sensors were not designed to detect. When present in great enough strength near a starship, the distortion could cause considerable damage, including a warp core breach.

In 2370 the USS Enterprise-D was nearly lost to a theta flux distortion, but was saved when an emergent lifeform on board the ship activated the warp drive and flew the ship out of harm's way. (TNG: "Emergence")