BACKGROUND: Evidence-based clinical guidelines have attracted international interest as tools for improving the quality of health care. Attitudes toward these guidelines are of great importance because attitudes are proven to be important predictors of guideline use. Attitudes are also believed to be shaped by perceptions of others, which makes the role of organizational implementation interventions interesting. AIMS: This article describes primary care nurses' attitudes toward guidelines among Finnish primary care nurses and the associations between attitudes, implementation interventions, and guideline use. METHODS: This study was a cross-sectional survey using postal questionnaires. Participants (N = 409) were primary care nurses working in outpatient services of primary health care centers in Finland. They were selected for the study from two groups of Finnish health centers representing contrasting implementation styles, for example, disseminator and implementer health centers (N = 32). RESULTS: Responses were received from 327 nurses. In general, nurses' attitudes toward guidelines were positive, especially those concerning the reliability and usefulness of guidelines. The utilization of any implementation intervention included in the questionnaire was associated with more positive attitudes. In addition, nurses working in health centers that used an active implementation strategy as opposed to a disseminator strategy also felt that others in their organization rated the guidelines more positively and that guidelines were more easily available. Further, nurses who were familiar or very familiar with the guidelines had more positive attitudes toward them. Attitudes were also associated with self-reported guideline use. CONCLUSIONS: The evidence-based guidelines were accepted as a reliable source of advice in patient care in Finnish primary care. It seems that implementation interventions improve attitudes toward guidelines and enhance guideline use. These interventions might also be important from another point of view; they presumably improve familiarity with guidelines, which was also associated with guideline use.