Diabetic feet ulcer is four times more likely to be found in patients who suffer from diabetes mellitus than in those who don't. Diabetic feet ulcer is one of chronic complications of diabetes mellitus which causes defects even deaths. Diabetes mellitus in one of the ten most frequent diseases in Indonesia. According to Riskesdas (Riset Kesehatan Dasar - Basic Health Research), the increment number of patients with diabetes mellitus from 2007 up to 2013 is 330,512.1 The research is aimed to find out the effect of oral hydrotherapy on risk reduction of diabetic feet ulcer in patients with type-2 diabetes mellitus. The research was done by applying quasi-experimental design (pre-test and post-test design with control group). By total population sampling, there were 68 respondents who participated. About 34 of the respondents were in experimental group at Dr. Soediran Mangun Sumarso of Wonogiri, and 34 respondents were patients who had check-ups at RS PKU Muhammadiyah of Surakarta. The research result shows that oral hydrotherapy can minimize risk reduction of diabetic feet ulcer in patients with type-2 diabetes mellitus significantly with p-value of 000.0 (α=0.005).