Background: Colostomy is a stoma which is formed after removing the large bowel or colon and is opening in the abdominal wall that's made during surgery. The care of patients with colostomy is a complex, challenging and lengthy process .The nurse can play a clinically relevant role in the care of patient undergoing ostomy surgery pre and post-operative education. Aim of the study: to evaluate effect of educational program on nurses' performance about colostomy care. Subjects &Methods: Research design: a quasi-experimental design was utilized to fulfill the purpose of this study.  Sample: Randomized sample conducted on 40 nurses caring for patient with colostomy .Setting:  two setting:  1^st setting at Oncology Center &2^ndsetting at Minia University Hospital. Tools: Two tools were used for data collection: First Tool: included two parts: part I: socio demographic data sheet for the nurses, part II: structured knowledge questionnaire second tool: observational checklist about colostomy care. Results: Reveled that the mean age of study sample was 32.95 ± 3.65, the majority (85%) of the studied sample had low knowledge before educational program implementation while, after 3 months of program implementation the majority (85%) had a good knowledge about colostomy care. Also all of study sample had weak performance before educational program implementation while, in post immediately of program implementation more than half of studied sample (52.5%) had accepted performance and after 3 months the majority of them had a good performance about colostomy care. Also, there was a highly statistically significant difference in nurses' knowledge and practice pre & post immediately and after 3 months educational program regarding colostomy care. Conclusion: The study concluded that, there was a positive effect of the educational program in improving nurses' knowledge and practices regarding colostomy care. Recommendations: Greater attention and closely observation from hospital on nurses′ performance during care for patient with colostomy and replication of the study should be done on a large sample.