Low back pain (LBP) is complained by dentists. It happened to dentists because they tend to work in static movements for a long time. In addition there are other factors which can trigger LBP as one of physical activity levels. This research aims to find out the association between the levels of physical activity and the incidence of low back pain. The research method used by researcher is analytical observation with cross-sectional research design. 76 dentist in Yogyakarta asked to be the sample for this research. The data collection method for the level of physical activity is done by distributing the questionnaire to respondent. Therefore, the data of low back pain was gained in the preliminary study. Both of physical activity level data and the incidence of low back pain data was analyzed by chi-square test. The data analysis shows there are two levels of physical activity with four results. The results are 24 respondents are positively indicated having LBP with mild physical activity level. Furthermore, 15 out of 76 respondents also positively having LBP with moderate physical activity level. However, 10 respondents are faced negative LBP with mild physical activity level. The last 27 respondents are negatively faced LBP with moderate physical activity level. The conversion of chi-square test shows a value of 9,147with a free degree of 1 and significance score of 0,002. This value is bigger than chi-square table value which is 3,841. It means there is significant association proportion between physical activity level with low back pain.