Background: proffesion is an assemble of task (work) which has been set to be worked by someone in order to earn a wage for a living. As we know, cleaning service and mechanics was very dissimilar kind of proffesion. Cleaning service mostly works indoor and only for a slight moment will work at outdoor. While mechanic works at outside of the building (outdoor) most of the time, which made them exposed by more pollutants such as carbon monoxide, plumbum, etc. these pollutants can affect both of the quality and quantity of the blood cells (leukocyte, eritrocyte, trombocyte, and etc) of those people whom being exposed by it for a such an amount of times. This research is needed to discouver leukocyte cells of cleaning service and mechanics Purpose: To discover the difference of leukocyte cells quantity between cleaning service and mechanis Methods: This research is an analytic observational study with a cross sectional design. This research was done by collecting blood samples of cleaning service at University Muhammadiyah of Yogyakarta and mechanics at their local garage in Bantul Yogyakarta in the range of August in 2016. The quantity of leukocyte cells are examined at the blood sample in Balai Laboratorium Yogyakarta. Total samples is 40 consisted of 20 cleaning service and 20 mechanics. Data is analyzed with saphiro wilk and independent t test. Results and Discussion: Average value of white blood cells count of cleaning service is 8,010 109/L and mechanics is 7,630 109/L. So, it conclude that average value of white blood cells count of cleaning service is higher than mechanics. There is no meaningful difference of white blood cells count between cleaning service and mechanics. It can be seen from the result of independent t test which showed p > 0,05 (p = 0,444). Conclusion: This research concluded that there is no difference of white blood cells count between cleaning service and mechanics