Aim To explore the use of paradigms as ontological and philosophical guides for conducting PhD research. Background A paradigm can help to bridge the aims of a study and the methods to achieve them. However, choosing a paradigm can be challenging for doctoral researchers: there can be ambiguity about which paradigm is suitable for a particular research question and there is a lack of guidance on how to shape the research process for a chosen paradigm. Discussion The authors discuss three paradigms used in PhD nursing research: post-positivism, interpretivism and pragmatism. They compare each paradigm in relation to its ontology, epistemology and methodology, and present three examples of PhD nursing research studies to illustrate how research can be conducted using these paradigms in the context of the research aims and methods. The commonalities and differences between the paradigms and their uses are highlighted. Conclusion Creativity and flexibility are important when deciding on a paradigm. However, consistency and transparency are also needed to ensure the quality and rigour necessary for conducting nursing research. Implications for research/practice When choosing a suitable paradigm, the researcher should ensure that the ontology, epistemology and methodology of the paradigm are manifest in the methods and research strategies employed. © RCN Publishing.