BACKGROUND: There is little evidence regarding attitudes to clinical decision support systems (CDSS) in oncology. AIMS: We examined the current usage, awareness, and concerns of Irish medical oncologists and oncology pharmacists in this area. METHODS: A questionnaire was sent to 27 medical oncologists and 34 oncology pharmacists, identified through professional interest groups. Respondents ranked concerns regarding their use of a CDSS on a scale from 1 to 4, with 4 being most important. RESULTS: Overall, 67% (41/61) responded, 48% (13/27) of oncologists and 82% (28/34) of pharmacists surveyed. Concerns included "difficulty defining complex clinical situations with a set of rules" (mean +/- SD) (3.2 +/- 0.9), "ensuring evidence base is up to date and relevant" (3.2 +/- 0.9) and "lack of clinically relevant suggestions" (2.9 +/- 0.9). Ninety-three percent reported using a CDSS but 54% were unaware of this. CONCLUSION: While there are benefits to using a CDSS, concerns must be addressed through user education. This may be a starting point for a user-centred design approach to the development of future local systems through a consultative process.