“This is the first reported study from SA on final year preregistration student nurses‟ self-reported depth of understanding of bioscience subjects and of their perceptions of the relevance of bioscience knowledge to their practice” (Rafferty, Kyriacos, 2016:43). Abstract Student nurses’ competence in applying bioscience to practice is under-researched in South Africa. This paper reports on two objectives of a longer study: (1) to describe final year nursing students’ self-reported depth of understanding of six bioscience subjects; and (2) their perceptions of the relevance of the bioscience subjects to their practice using descriptions of personal critical incidents and picture interpretations of three nursing activities. A descriptive observational survey was employed using a self-administered questionnaire at a one-time point in a classroom in a nursing college in Cape Town, South Africa in 2013. A sample of 76/236 (32.2%) fourth-year students participated. Results showed that