BACKGROUND AND OBJECTIVE The 10th National Economic and Social Developmental Plan considered quality of human. Quality of human life was affected by quality of working life (QWL). Professional nurses had responsibility for patients' quality of life. Thus, professional nurses should have a quality of working life more effectively before they could help patients. Personal factors have relationships with the quality of working life. Thus, the present study was to describe the level of the QWL, to examine the relationships between job characteristics, organizational climate, organizational commitment, and job satisfaction with the QWL and to predict the QWL among professional nurses at Phramongkutklao Hospital. MATERIAL AND METHOD Two hundred and thirty-one professional nurses, who had worked for at least 3 years, were selected by stratified random sampling from 12 departments at Phramongkutklao Hospital. The questionnaires were developed, consisting of personal factors, job characteristics, organizational climate and commitment, job satisfaction and QWL. Content validity was examined by 9 experts. Reliability was obtained at 0.97 by means of Cronbach's alpha coefficient. RESULTS The over all mean score of the level of quality of working life among professional nurses was at a moderate level (mean = 3.412, SD = 0.459). Personal factors were age, status, education, position, experience, salary and wards were no relationships with the QWL. Job satisfaction was positive and related at a high level, while organizational commitment, organizational climate, and job characteristics were positive and related at a moderate level to the QWL significantly at 0.001 level (r = 0.724, 0.694, 0.640, and 0.334). Multiple regression analysis factors affecting QWL indicated that professional nurses associated negative factors with job characteristics and positive factors with job satisfaction, organizational commitment, and organizational climate at 62.10 percent (R2 = 0.621). QWL = 0.762 + 0.336 Job satisfaction + 0.265 Organizational climate + 0.250 Organizational commitment - 0.118 Job characteristics. CONCLUSION In order to develop the QWL among professional nurses at Phramongkutklao hospital, nursing administrators should promote their job satisfaction, organizational commitment, organizational climate, and job characteristics. Professional nurses who have better QWL, are more likely to stay in their positions and provide better nursing care.