This exploratory study in the field of nursing informatics examined the usage of information technology, namely on-line access to Medline in clinical settings, by a convenience sample of 121 nurses from a large university hospital. A descriptive correlational design was used. Guided by the conceptual framework of Nurse-Computer Interaction (Staggers and Parks, 1991) and based on variables set forth in the Theory of Reasoned Action (Azjen and Fishbein, 1980), the study tested hypotheses regarding attitudinal and normative influences on reported use of on-line bibliographic retrieval systems. It was also hypothesized that using MEDLINE could increase and improve nurses' decision-making confidence and their adoption of nursing research findings. Consistent with the Theory of Reasoned Action, multiple regression analyses were conducted on nurses' responses to survey questions to test hypotheses--that those who register more favorable attitudes towards computers and nursing research and those who perceived subjective norms more supportive of computers and nursing research would have a higher reported use of the MEDLINE system. Findings were significant (F = 9.12, p =.003) and supported the hypothesis that nurses' attitudes towards research influenced MEDLINE usage. To determine if there was a significant relationship between MEDLINE usage, decision-making confidence and research use, regression analyses were also performed. Findings indicated that MEDLINE usage was significantly related to both nurses' research utilization (F = 7.39, p =.0076) and nurses' decision-making confidence (F = 40.62, p =.0000). MEDLINE usage accounted for 25.4% of the variance in decision-making confidence. This study represents a beginning work in the field of nursing informatics to address the many complex variables inherent in human-computer interactions. Findings suggest the need for further research to document the benefits of information technology for nursing professionals.