This research was a survey research with the objectives to assess the knowledge, attitude, and practice of preventive self-care on diabetic foot ulcer in type II diabetic patients, Muang Roi-Et District, Roi-Et Province, Thailand. Data collection was between September to December 2009. The samples were registered diabetic type II patients at Diabetes Mellitus Clinic at Roi-Et Hospital according to their registration numbers ID (DM) for a number of 300 respondents by quota sampling. The research tool was an interview form in 4 parts. The overall reliability value was 0.758. Statistics in use by SPSS version 17 were frequency, percentage, mean, standard deviation, and Chi-square test. The result revealed that most of the respondents were female (67.3%), aged between 55-60 years old (41.7%) (mean age 53 years). They were married (76.0%), finished primary school (59.0%), and were agricultures (30.0%). Average number of their family members was 4. Average income was 15,682 baht monthly with 10,702 baht monthly expenses. Family members did not have diabetes mellitus history (45.3%) and never had foot ulcer unconsciously (80.3%). The respondents had their knowledge level on preventive self-care part for 66.0% (moderate level), had their attitude level on preventive self-care part for 75.3% (high level) and their practice on preventive self-care part for 50.7% (high level). Factors associated with preventive self-care part at the level of 0.05 were gender (0.021), occupation (0.005), household expense (0.008), knowledge (0.000) and attitude (0.000).