Background Antibiotic resistance is a public health concern worldwide. A high proportion of antibiotics are prescribed in primary care, often for conditions where there is no evidence of benefit. Without a change in these prescribing patterns, resistance will persist as a significant problem in the future. Little is known about how trainees in general practice perceive and develop their prescribing. Aim To explore the attitudes of trainees in general practice towards antibiotic use and resistance, and the perceived influences on their prescribing. Design and setting A qualitative study of 17 vocational trainees in general practice (GP registrars) in both rural and urban areas in Australia employing semi-structured interviews and a focus group. Method Maximum variation purposive sampling of GP registrars from diverse backgrounds and training stages continued until thematic saturation was achieved. Topics of discussion included awareness of antibiotic resistance, use of evidence-based guidelines, and perceived influences on prescribing. Transcribed interviews were coded independently by two researchers. Data collection and analysis were concurrent and cumulative, using a process of iterative thematic analysis. Results Registrars were aware of the importance of evidence-based antibiotic prescribing and the impact of their decisions on resistance. Many expressed a sense of dissonance between their knowledge and behaviours. Contextual influences on their decisions included patient and system factors, diagnostic uncertainty, transitioning from hospital medicine, and the habits of, and relationship with, their supervisor. Conclusion Understanding how trainees in general practice perceive and develop antibiotic prescribing habits will enable targeted educational interventions to be designed and implemented at a crucial stage in training, working towards ensuring appropriate antibiotic prescribing in the future.