Background: A senior-friendly hospital focuses on providing geriatric care through support and responds to a senior’s physical and cognitive needs and develops knowledge, skills, and attitudes of nurses and other health professionals to be fully maximum in their care. Aim: Evaluate the effect of designed nursing instructions on the knowledge and attitude of elderly Care nurses and assessment of senior-friendly Hospital criteria. Research design: One group pre-posttest quasi-experimental Setting: The study was conducted at the Cardiac and Digestive System Center in Sohag City. Sample: A simple random sample of 42 nurses was included. Data collection tools were Tool (I): Structured interview questionnaire about personal data and work-related factors. Tool (II): Knowledge assessment questionnaire. Tool (III): Multifactorial attitude of health care professionals toward older people questionnaire, Tool (IV): Senior-friendly hospital criteria checklist. Results: The mean scores of participants’ knowledge and attitude regarding elderly care had a high statistically significant difference (t = 29.806, p = 0.001) in pre- and post-training programs. More than half (59.5%) of the participant nurses precepted their hospital as a senior-friendly hospital with a strong positive significant relation between knowledge and participant nurses’ perception of senior-friendly hospital criteria (r=0.575, p=0.002). Conclusion: The application of designed nursing instructions is highly effective in improving the knowledge and attitude of nurses regarding care of elders, which enhances the hospital's chance to be a senior-friendly hospital. Recommendations Hospital managers should set a hospital policy on adherence to senior-friendly hospital criteria and training for all health professionals for providing elders’ care. Keywords: Attitude, knowledge, nursing instructions, and older, senior-friendly hospital