Purpose: The elderly are often faced with multiple diseases, in particular hemodialysis (HD) which requires many kinds of medication. This study examined the factors influencing the behavior of taking medicine in elderly patients undergoing HD. Subjects and Methods: The subjects comprised 70 outpatients > 65 years undergoing HD (48 male and 22 female). The mean age of the patients was 72.5 ± 4.4 years. The mean duration of dialysis history was 6.1 ± 5.2 years. We performed a questionnaire survey using Medication Assessment Tool, The Kidney Disease Quality of Life (QOL)-Short Form and Acceptance for Dialysis Instrument. Result: Two factors related to poor behavior of taking medicine: dialysis history < 2 years and poor acceptance of dialysis. The multiple regression analysis showed patient satisfaction (β = –0.329, p < 0.01) and symptoms/problems (β = –0.273, p<0.05) as significant independent variables relating to behavior of taking medicine. Conclusion: Poor behavior of taking medicine is related to a short dialysis period, poor acceptance and poor satisfaction of dialysis therapy in elderly patients.