The study entitled "Impact Assessment of Disciplinary measures on staff performance in Kaduna State Water Board Zaria, City District and Sunseed Nigeria Limited was informed by the concern on the negative trends of staff indiscipline and failure to effectively apply disciplinary measures and procedures, particularly in the public organizations which affects staff morale and performance. It was against the foregoing background, that, the study focuses on the comparative (Private & Public) impact assessment of discipline on staff performance and the extent to which ineffectiveness to apply disciplinary measures and procedures leads to increase in the perpetuation of indisciplinary acts, which is a threat to the progress and growth of particularly public organisations. Data for the study were collected from both primary and secondary sources. The primary source comprises the use of questionnaire, interview and observation, while the secondary sources consist of text books, journals, thesis, manuals and other unpublished papers. Descriptive and inferential statistical tools were used for data presentation and analysis. The chi-square (x2) non parametric tool was used for the analysis of data that leads to the testing of the two hypotheses. From the data presented and analyzed, it was revealed among others that, termination and dismissal and other less severe disciplinary measures were low in Kaduna State Water Board Zaria, City District because supervisors derelict from applying disciplinary measures, while it is low in Sunseed Nigeria limited because there is excessive monitoring of staff by their immediate supervisors and the signing in and out of a register, in reporting and leaving work place; also inconsistency in application of disciplinary measures and procedures affects staff morale and performance, particularly in the public sector (Water Board) which by extension manifests into hatred and insubordination. Based on the findings, it was recommended among others that management should make use of discipline as punitive measure particularly as friendly methods and counseling do not suffice in reversing the trend in public organizations; and to that effect, disciplinary procedures should be preceded by advance warning, and the length of time between misconduct and discipline should be short and consistent; finally merit and competency, should not allow to pave way to loyalty and affiliation in the recruitment process in order to get the right caliber for the right job towards higher performance