BACKGROUND: The sizable fraction of the elderly adults who are left without Part D coverage indicates there are potential barriers in taking up Part D, including information barriers and economical barriers. Few studies have examined how cost-related medication nonadherence (CRN) affected the willingness of taking up Part D among elderly adults using national representative data. OBJECTIVES: To estimate the impact of self-reported CRN on the decision of taking up Medicare Part D among Medicare beneficiaries age 65 and above who did not have Part D coverage in 2006 incorporating the effect of complex sample survey design. METHODS: This retrospective cross-sectional study used data from the 2006 Health and Retirement Study database (2006 HRS). Information on patient demographics, social and economic factors and health insurance coverage were obtained by survey. The dual-eligible beneficiaries were excluded due to automatically enrollment. A total of 5,826 eligible cases were recruited in our study. RESULTS: The majority of the eligible Medicare beneficiaries responded “not at all likely” to take Part D (62%), and significant proportions also reported “not too likely” to take Part D (21.46%), while few of them reported “somewhat likely”(9.44%) and “Very likely”(6.31%). Results of weighted cumulative logit regression indicated that people who had cost barriers in medication use were significantly more likely to take up Medicare Part D (OR=2.62, 95% CI[2.00, 3.44], p<0.001). Males and older adults were less likely to take up Medicare Part D (OR=0.83, 95% CI[0.74, 0.94] and OR=0.98, 95% CI[0.97, 1.00], p<0.01). CONCLUSIONS: Results of this study indicated experiencing CRD was significantly associated with the probability of taking up Part D. CRN could be a motivation of taking up Part D. Thus, characteristics of beneficiaries who reported having CRN, especially those who continued to experience CRN after taking up Part D, need further studies.