The 4th Artillery Regiment (Portuguese: Regimento de Artilharia N.º 4, RA4) OTE is a base unit of the Portuguese Army, stationed in Leiria.

Presently, the RA4 is dependent on the Rapid Reaction Brigade, whose charges towards Operating System Component Forces.

[1][2] Regimento de Artilharia n.º 4 - translated http://www.exercito.pt/SITES/RA4/Paginas/default.aspx Archived 28 July 2014 at the Wayback Machine - translated https://web.archive.org/web/20150924020310/http://www.g-sat.net/showthread.php?444233-Historia-Regimento-de-Artilharia-n%C2%BA-4-(Leiria) - translated