Background: Unmet need for contraception remains high in Ghana, but the predictors of this are yet to be adequately documented. Knowing the level of unmet need for contraception and the factors that predict this unmet need is essential in assessing and forecasting the contraceptive needs of the nation. Methods A community-based cross-sectional household survey was nested into the routine data collection of the Kintampo Health and Demographic Surveillance System (KHDSS). The data were collected from July to December 2011. A total of 3308 married and cohabiting women residing in the Kintampo area of Ghana were studied to determine the magnitude of contraceptive use, the level of unmet need for contraception and the predictors of this unmet need. Using the KHDSS’s sampling frame of women in their reproductive age, simple random sampling was used to select 3308. This sample size was calculated based on the magnitude of unmet need for contraception in Ghana and the estimated level of unmet need in the study area. Women aged 15-49 years who resided permanently in the area and were married or in cohabitation qualified to be studied. Results Nine hundred and fifty two (28.8%) of the respondents were contraceptives users. Three hundred and thirty six women were pregnant, 95 of these pregnancies (2.9%) were unintended. Women who wanted to wait for more than 2 year before conception or had unintended pregnancy in the last 2 years or wanted no more child birth or were not sure of wanting more children were categorized as having unmet need. These women were 938 in number, unmet need was estimated at 28.3%. Fifty two (1.6%) of the pregnancies were wanted but at a later time whereas 43 (1.3%) were unwanted. Age, fear of side effects and level of education were the significant predictors of unmet need. Older women had lower odds of her having unmet need; compared with the women aged 15-19 years. Women aged 25-34 years were 70% less likely to have unmet need (AOR= 0.3, 95%CI: 0.12-0.99, p=0.02). Women with middle/Junior high school education were 20% less likely to have unmet need compared with women with no education/primary education, (AOR=0.8, 95%CI: 0.69-0.95, p=0.01). The risk of unmet need was significantly less when women with secondary education/ higher education were compared with the women with no education or primary education (AOR= 0.5, (95%CI: 0.38-0.77, p<0.01). A woman with fear of side effects was 3.5 times more likely to have unmet need than a woman who did not express any fear (OR=3.5, 95%CI: 2.5-5.0, p <0.01). Key recommendations Programs that will alleviate the fear of the side effects of contraceptives will go a long way to enhance contraceptive uptake and reduce unmet need for contraception