Construction industry in Ethiopia is growing fast, but also has problems like time overrun, cost overrun and productivity problems in many of the projects. In construction projects the resources used in construction phase of each activity are the key factors that determine the total project cost and time. Among these labor productivity is vital for overall productivity and success of a project especially for developing countries like Ethiopia, where most of the building activities are performed by a huge amount of labors or it is labor intensive. In order to improve these labor productivity, it has to be measured and standardized properly. Due to this reason Ministry of Urban Development and Housing prepared a document entitled building construction output norms in Ethiopia in 1995 aimed at assisting and providing information and data needed for those involved in the construction industry. However, these output norms were not taken from actual site measurement and it is being used in current construction industry. The objective of this research is comparing the actual man-hour values and the Ministry of Urban Development and Housing’s theoretical man-hour values, to rank activities with high difference when their actual and theoretical man-hour values are compared, determining productivity baseline by using Thomas’s and clustering baseline approaches for 20cm HCB work, 3 coats of plastic paint, 60cm*60cm ceramic tile, two coats of plastering and super structure concrete work ,assessing current practice of using these norms by public building projects in Bahir Dar, and showing the gap between the theoretical man hour norm set by Ministry of Urban Development and Housing and actually registered man hour values of labor productivity in public building construction projects in Bahir Dar. Data were collected from both primary and secondary sources. The primary data were obtained through work sampling technique, actual site visit, questionnaire and interview. The secondary data were obtained from previously done different researches, internet sources, journals, books, reports and various articles. The finding from questionnaires showed that almost all public buildings in Bahir Dar are using theoretical man-hour value by Ministry of Urban Development and Housing for tendering, scheduling and planning, estimation of project cost and time and for controlling and monitoring purposes. Labor intensive and common civil works were listed and let the respondents to give the degree of differences compared with the norm (very low difference, low difference, moderate, high difference and very high difference). By their scored Relative Importance Index value the top ten activities were selected to detail iii comparison by measuring their actual man-hour productivity measurements. After ranking the activities the researcher selected the top 10 activities and actual site measurement was taken for 15 working days. However, the only 5 activities were on progress i.e. 20cm HCB work, 3 coats of plastic paint, 60cm*60cm ceramic tile, two coats of plastering and super structure concrete work on the time of data measurement; whereas back filling work, trench excavation work, 50cm stone masonry above natural ground level, Sub structure concrete work and 5cm cement screed were not active on that time. After getting hourly productivity output their actual productivity baseline value were determined. The actual productivity for selected work items ( 20cm HCB work, three coats of plastic paint, 60cm*60cm ceramic floor tile, two coats of cement mortar plastering and super structure c-25 concrete) were: for 20cm HCB work = 1.4m 2 /hr, for three coats of plastic paint work = 3.125 m 2 /hr, for 60cm*60cm ceramic floor tile work = 2.05 m 2 /hr, for two coats of cement mortar plastering = 1.85 m 2 /hr and for Super structure concrete work = 2.96 m 3 /hr. One sample t-test SPSS software to was used to decide whether It is essential to revise the norm or not. The p values of all analyzed five activities by one sample t-test were less than 0.05. The result revealed that there are significant differences between Ministry Of Works and Urban Development Norm and actual man hour productivity value. Therefore, updating these man-hour values is important. Key words; Building, Construction, Labor, Man-hour productivity, Norm, Schedule