Despite recent advances in knowledge and improvements in the technology of the hemodialysis, the prognosis of patients receiving hemodialysis (HD) remains poor due to in insufficient knowledge about nutrition which result in interdialytic weight gain. Education enables hemodialysis patients overcome interdialytic weight gain, correct the nutritional habit, improve knowledge, and awareness. Aim of the study: to evaluate effect of hemodialysis patientsˊ knowledge related to types of food rich fluid on interdialytic weight gain among hemodialysis patients. Method: quasi experimental study design was used. Setting: New General Mansoura Hospital. Purposive sample of this study composed of 70 adult hemodialysis patients who met inclusion criteria included in this study. Tools: two tools used in this study, hemodialysis patients' knowledge questionnaire about types of food rich fluid & interdialytic weight gain measurement. Results: the result revealed significant improvement in hemodialysis patients' knowledge related to types of foods rich fluid which was poor (mean ± SD = 2.17± 2.25) during pre test, and good (mean ± SD = 6.78± 2.24) during poet test. There was significant reduction of interdialytic weight gain. Conclusion: increase hemodialysis patients knowledge about types of foods rich fluid has a positive effect on reduction interdialytic weight gain.