Naphtholactam is an organic compound derived from naphthalene.

It is a tricyclic species consisting of a naphthalene core fused with a lactam (NH-CO-) at the 1,8-positions.

It is a precursor to the dye anthanthrone via ring-opening to the amino carboxylic acid, which can be converted to the diazonium salt.

Naphthostyril derivatives are also of interest in medicinal chemistry.

The lactam condenses with anilines in the presence of phosphorus oxychloride.