A 37-year-old male was pronounced dead inside of the home.
Neighbors tell Action News the men were first arguing outside of the home then went inside where the fatal beating occurred.
Police are still investigating and have not decided whether to charge the roommate.
Investigators say the victim apparently was under the influence of drugs and started to attack the roommate, who struck his roommate in self-defense, killing him.
Click here to get the latest Philadelphia news and headlines from across the Delaware and Lehigh valleys.