Background: Out of ten married women or in-union women one in most regions of the worldrnhas an unmet need for family planning; that is to say, they are required to give up or laternchildbearing but to prevent pregnancy they do not use a modern contraceptive method. Despiternincreases in contraceptive use in developing countries, the total number of women with unmetrnneed remains high and has even increased slightly, from 210 million in 2003 to 225 million inrn2014. In Ethiopia unmet need for family planning for currently married women, age 15-49 isrn22%. That is more than 1 in 5 married women in Ethiopia who have an unmet need for familyrnplanning. The objective of this study was to assess the changes in family planning practice,rnexplain the changes in the level of unmet need for FP to analyze demographic, socioeconomic,rnand institutional determinants of unmet need for FP among married women between EDHS 2000rn- 2016 surveys in Oromia region.rnMethod: Data was obtained from the Ethiopian Demographic and Health Surveysrn(EDHS)performed in 2000, 2005, 2011, and 2016. Data concerning a total of 5,830 currentlyrnmarried women, aged 15-49, was considered in the analysis. The data from all EDHS wasrncollated so as to follow the trends throughout the period considered for the survey. Descriptivernanalysis was used to examine the trends and multivariable logistic regression was used tornidentify factors associated with unmet need for both spacing and limiting and binary logisticrnanalysis was used to identify factors associated with total unmet need.rnResults: Results show that the total unmet need for contraceptives in the Oromia region wasrngenerally declining overtime except for 2005 when it tended to rise. That is it was 38.7% forrn2000, 41.3% for 2005, 30.7% for 2011, and 28.3% for 2016. Unmet need for family planningrnshows a declining trend with women who had no media exposure (radio and TV) across the fourrnEDHS. The major reasons for not using contraception were the women wanting more children,rnreligious prohibition, and fear of side effects, respondent and husband opposition to using, andrnwoman sub-fecundity or infecundity. The multivariable analysis identifies higher odds of unmetrnneeds among women at younger age, primary education, living in rural area, no media exposurernabout family planning and for currently working women. Also the analysis shows lower odds ofrnunmet need for women with small number of children, older age at first intercourse and largernnumber of ideal children.rnConclusion and recommendation: There was a higher level of unmet need in the Oromiarnregion in all four surveys. The level of unmet need in rural residents was higher than that ofrnurban residents. The finding shows family planning messages had a positive effect on unmetrnneeds. Therefore, the government is recommended to increase family planning messagesrndelivered through radio, TV, and health facility workers during ANC, PNC, delivery, andrnimmunization.