This exploratory study investigated nurses' self-assessment of their own nursing competencies, job demands and job performance in Taiwan. Nurses' self-evaluation on their own job performance was conceptualized as an indicator of nursing care quality. A total of 21 competencies were clustered into three groups: basic-level patient care skills, intermediate-level patient care and fundamental management skills, and advanced-level patient care and supervision skills. Nurse subjects were randomly selected from the member roster of Kaohsiung Nurse Association; 850 nurses were invited to participate and questionnaire packets were sent to their homes. The overall response rate was 35.8%. Multiple regression analyses found that nurses' self-assessment of intermediate patient care skills, the difference between nurses' self-assessment and job demands for basic patient care skills, and nurses' overall satisfaction with their own nursing competencies were three significant predictors of overall satisfaction with nurses' own job performance. Nurses' self-assessment on basic patient care skills and advanced patient care skills contributed to nurses' levels of overall satisfaction with their own nursing competencies. These results suggest a relationship between competency and performance. These findings may serve as a guide to amend academic nursing courses and on-job training programs as appropriate to place a greater emphasis on the competencies desired for providing high quality of nursing services.