The overall hexa-gonal framework of the title compound, penta-sodium ammonium trimanganese(II) borophosphate sesquihydrate, consists of tube-like borophosphate anions, (∞) (1){[B(3)P(2)O(11)(OH)](4-)}, made up of corner-sharing PO(4) and BO(4) tetra-hedra and BO(2)(OH) triangles, forming ten-membered ring windows. The tubes are inter-connected via distorted MnO(6) octa-hedra, establishing a three-dimensional open-framework structure with two different types of ring-channels (12- and six-membered) that run along [001]. The 12-membered ring channels are occupied by NH(4) (+) ions and water mol-ecules. The ten-membered ring windows in the walls of the tubes are occupied by Na(+) ions. The remaining Na(+) ions and the water mol-ecules, one of which is half-occupied, reside within the six-membered ring channels. The structural setup is consolidated by an O-H⋯O hydrogen bond between the OH group and an opposite O atom of the framework. Donor-acceptor distances ranging from 2.80 to 3.35 Å between the ammonium N atom, water O atoms and framework O atoms indicate further hydrogen-bonding inter-actions.