The purpose of this study was to evaluate the nurses' work performance before and after implementation of two nursing information subsystems: Patient Admission Nursing Documentation(PAND) and Physical Examination Documentation(PED) in 2351 beds medical center in Taiwan. Nurses' work performance was measured by time observation. The results of research showed that PAND increased the nurses' work performance 19.7% and PED increase the nurses' performance 2.8%.