We assessed the cumulative conversion rates (CCR) from minor cognitive impairment (MCI) to dementia among individuals who failed to participate in annual screening for dementia. Additionally, we analyzed the reasons for failing to receive follow-up screening in order to develop better strategies for improving follow-up screening rates. We contacted MCI patients who had not visited the Dongdaemun-gu Center for Dementia, a center established by Seoul city for early detection of dementia patients, for annual screening during the year following their registration. We compared the CCR from MCI to dementia in the following two groups: subjects registered as having MCI in the Dongdaemun-gu Center for Dementia database and subjects who failed to revisit the center, but who participated in a screening test for dementia after being contacted. The latter participants completed a questionnaire asking reasons for not previously visiting for follow-up screening. The final diagnoses of the 188 subjects who revisited the center only after contact were 19.1% normal, 64.9% MCI and 16.0% dementia. The final diagnoses of the 449 subjects in the Dongdaemun-gu Center for Dementia database were 25.6% normal, 46.1% MCI and 28.3% dementia. The CCR of the revisit-after-contact group was much lower than anticipated. Among the reasons for not revisiting the center, “ no need for checkup” was the leading reason by 28.2%, followed by “other by 23.9% and “forgot the date” by 19.7%. The 45 subjects who answered “other” further reported the following reasons: 9 responded “there was no call from the center,” 3 responded “I was too busy,” 2 responded “I didn’t know I had to take a test,” 1 responded “personal reasons,” and 29 left the reason blank. Considering the low dementia detection rate of the group who revisited only after contact and the reasons they gave for noncompliance, there appears to be a need for ongoing outreach and education regarding the course and prognosis of MCI. Active publicity and detailed education for the public, along with secure personnel and budget may be crucial for detection improvement.