The hospital waste water is potential as a medium of the diseases infection and environmental pollution. Therefore, to reduce the potential, there should be a good and proper management existence of the waste water treatment installation or the waste water  treatment unit. This research is objected to study about the difference of the contents of BOD, COD, TSS, coli bacteria on the waste water before and after the treatment in RSUD Nganjuk. This research was an observational investigation,and a cross sectional research. The samples were taken from 2 points that was on the inlet bath, and the outlet bath. The mean results after the treatment were compared with the quality standard of waste water as included of the East Java Governor, number 61, 1999, on the waste water quality standard for the hospital activities.

There were significant differences before and after the treatment for the average of BOD and COD  Its conclude that performance of waste water treatment plant at RSUD Nganjuk can be optimal by re-activate the chlorination that has been long not functioned, and to improve the maintenance of the machines operation in accordance with the working procedure.

Keywords : BOD, COD, MPN Coliform , TSS, Waste water