A sanitary wall installation connection box unit, including a box housing body having a rear-side base portion and a sleeve portion projecting to the front from the base portion, which sleeve portion peripherally surrounds a sanitary component mounting space, which space is accessible via an open front end face of the sleeve portion, and a connector body disposed on the base portion of the box housing body, which connector body includes a sanitary component connection contour facing the sanitary component mounting space, a fluid line connection interface structure accessible on an outer side of the box housing body, a fluid conduit structure for fluid connection of the fluid line connection interface structure to the sanitary component connection contour and at least one electric line feed-through opening leading from an outer side of the connector body through the connector body to the sanitary component mounting space. Illustratively, the base portion of the box housing body is made of a sealing resilient material at least in an electric line connection region adjacent to the electric line feed-through opening of the connector body, and the electric line feed-through opening of the connector body is covered on an outer side by a closure membrane made of the sealing resilient material of the electric line connection region of the base portion.