Background: Diabetic foot ulcer is a serious complication of diabetes and a major cause of morbidity and mortality among diabetic elderly patients, and good prevention guideline programs will inhibit the diabetic foot ulcer and further complication. Aims: This study aimed to evaluate the effect of a foot ulcer prevention guideline program for elderly diabetic patients at EL- Fayoum General Hospital. Research design: A quasi-experimental research design was used to utilize this study. Setting: The study was conducted at the medicine outpatient clinic in EL- Fayoum General Hospital. Subjects: A purposive sample was used to choose 300 elderly diagnosed with diabetes. Tools for data collection: Two tools for data collection were used. 1st tool: Structured interviewing questionnaire included demographic characteristics of elderly patients, past and current medical history, knowledge assessment questionnaire, patients reported practice questionnaire. 2nd tool: Observational checklist to assess foot ulcer risk included neurological foot assessment and peripheral vascular assessment. Results: It was revealed that there was a highly statistically significant improvement in total knowledge, good score and satisfactory reported practice represented as (7% to 85.3%) and (40.3% to 93.30%) respectively pretest versus posttest. In addition, there was a highly statistically significant improvement in total neurological foot items and total right and left peripheral vascular items represented as (14.23±3.004 to 16.97±1.800), (11.38±2.57 to 12.22±2.11) and (11.32±2.63 to 12.15±2.14) respectively pretest versus posttest. Conclusion: The current study concluded that after applying the foot ulcer prevention guideline program, level of knowledge, reported practice and foot ulcer risk scale of elderly diabetic patients improved. Recommendation: Periodic prevention guideline program and reduction sessions regarding the prevention of foot ulcer in diabetic elderly patients.