Tubular post and rail fencing system

A tubular post and rail fencing system having a plurality of generally upright posts interconnected with one or more generally horizontal rails that connect to the posts so as to reduce the cost and time of installation. The posts have an upper and lower rail aperture for receiving an end section of the upper and lower rails, respectively. The end sections of the rails have a rod hole therethrough that is disposed in an interior chamber of the post when the rails connect to the posts. The lower end of a locking rod is inserted through the rod holes. The upper end of the locking rod is configured to keep the locking rod in the rod holes and secure the rails to the post. A post cap is placed on top of the posts. A gate can be easily and quickly added to the fence between any pair of posts.