en Aim: Patients' satisfaction (PS) is a dominant concept in medical care, due to the gap in the literature on Persian version of PS instruments, this study has conducted with aim to analyze the validity and reliability of self-designed Najmiyeh Inpatient Satisfaction Questionnaire (NISQ). Methods: This study was carried out on 247 inpatients that came in Najmiyeh subspecialty hospital in Tehran (the capital city of Iran) during year 2011 who were selected by proportional stratified sampling method. Statistical analysis used: In this study, after checking content validity we used confirmatory and explanatory factor analysis and Cronbach's Alpha in order to examine construct validity and reliability, respectively. SPSS (version18) and AMOS (version 20) programmer were used to analyze data. Findings: Samples consisted of 247 subjects (222 women (90%) and 25 men (10%)). The explanatory factor analysis showed 5 factors with 64% total variance and 0.91 Kaser-Meyer-Olkin Index, the result also confirmed with confirmatory factor analysis (PNFI=0.71, RMR=0.03, PCFI=0.76). Extracted factors consisted of: “satisfaction from nursing services and their behaviour”, “satisfaction from one’s doctor”, “satisfaction from inpatient department”, “companions’ satisfaction”, “satisfaction from one’s room”. Also the questionnaire’s reliability was 0.96 using the Cronbach's Alpha method. Conclusions: Because validity and reliability indexes of NISQ were reported in suitable range, we can confirm that this questionnaire is a valid and reliable tool for measuring inpatient satisfaction. Inpatient Satisfaction,Reliability,Validity,Questionnaire 37 45 http://hehp.modares.ac.ir/browse.php?a_code=A-5-1000-4005&slc_lang=en&sid=4 Mohammad Gholami Fesharaki Mohammad Gholami Fesharaki 100319475328460051236 100319475328460051236 Yes Department of Biostatistics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran Department of Biostatistics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran Mohammad Javad Jamali Mohammad Javad Jamali 100319475328460051239 100319475328460051239 No Department of Education & Research, Najmieh Hospital, Baqiyatallah University of Medical Sciences, Tehran, Iran Department of Education & Research, Najmieh Hospital, Baqiyatallah University of Medical Sciences, Tehran, Iran Fatemeh Rahmati Najarkolaei Fatemeh Rahmati Najarkolaei 100319475328460051240 100319475328460051240 No Health Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran Health Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran Masome Mohamadian Masome Mohamadian 100319475328460051241 100319475328460051241 No Department of Education & Research, Najmieh Hospital, Baqiyatallah University of Medical Sciences, Tehran, Iran Department of Education & Research, Najmieh Hospital, Baqiyatallah University of Medical Sciences, Tehran, Iran Zohreh Aghamiri Zohreh Aghamiri 100319475328460051242 100319475328460051242 No Department of Education & Research, Najmieh Hospital, Baqiyatallah University of Medical Sciences, Tehran, Iran Department of Education & Research, Najmieh Hospital, Baqiyatallah University of Medical Sciences, Tehran, Iran Mehdi Habibi Mehdi Habibi 100319475328460051243 100319475328460051243 No Iran Helal Institute of Applied Science & Technology, Tehran, Iran Iran Helal Institute of Applied Science & Technology, Tehran, Iran