With the fast development of computer software and hardware, technology application is ubiquitous, and many healthcare services have integrated a clinical information system into daily practice. With today's information technology, everyone should possess basic computer competency to meet on-the-job demands and especially to use an information system in healthcare. Thus, the purpose of this study was to explore Taiwanese nurses' computer competency, the interface usability, and any change in the nurses' practice pattern as a result of the technology use. The current study adopted a descriptive research design, recruiting 114 nurses in medical and surgical ICUs to survey their technology use. Additionally, a total of 6780 observation values were obtained by a work sampling method to investigate the applicability of the information system. The results indicated that nurses with a higher education can use more computer applications and had better computer competency than other nurses. Additionally, computer competency was related to interface usability, and interface usability in the surgical ICU was rated higher than those in the medical ICU. Finally, the nursing practice patterns observed were related to the technology use. The results could serve as a reference for information technology usage evaluation in nursing.