Back ground: Reproductive health implies that people have the capability to reproducernand the freedom to decide if, when and how often to reproduce. Sub-Saharan Africarncountries face the highest birth rate and population growth rate in the world and Ethiopiarnis one of the countries with a high population growth rate, and it has become one of the rnmost populous countries in Africa.rnIt is obvious that solutions are necessary to slow down the rapid rate of population rngrowth all over the world including developing countries. Despite the availability ofrnfamily planning services in health facilities the unmet need for family planning in OromiarnRegional State however, remains high. rnObjectives: the objective of this study is to assess the magnitude of unmet need forrnfamily planning and associated factors among currently married (in union) women ofrnreproductive age in Woliso district, South West Shoa Zone, Oromia National Regional rnState. rnMethods: Community based cross-sectional study was conducted from January to rnJune 2013. Multi stage sampling technique was used, by using systematic samplingrntechnique 875 respondents were selected from six kebeles. Both quantitative andrnqualitative data collection methods were employed. Data entry and cleaning was donernby EPI INFO v3.5.1 and analysis was done using SPSS v16 statistical packages.rnDescriptive analyses using frequency and percentage were performed to describe thernstudy population. Bivariate analysis with OR and 95%CI was done to determine thernpresence and magnitude of an association between independent variables and the mainrnoutcome variable (unmet need). Multivariate logistic regression analysis was done torndetermine independent predictors of unmet need. A cut-off point for significance was setrnat a P-value of less than 0.05. rnResults: In this study the prevalence of modern contraceptive use among currentlyrnmarried women was 56.4% which is much higher than the national and Oromia regionalrnstate. Unmet need for family planning was found to be 21.1%, of which 13.6% was forrnspacing and 7.5% for limiting. Unlike other study, socio-demographic characteristicsrnsuch as age at first marriage, age at first pregnancy, and Occupational status, were notrnfound to be associated while religion, ethnicity and number of children a woman everrnhad showed significant association with unmet need for family planning. rnConclusion: Generally, this study indicated that the contraceptive prevalence in thernstudy area was higher than that of national and Oromia. Religion, ethnicity and numberrnof children a woman ever had been found to be factors associated with unmet need forrnfamily planning.