Objective Pathology overutilisation is a significant issue affecting the quality and cost of health care. Because junior medical officers (JMOs) order most pathology tests in the hospital setting, the aim of the present study was to identify the main reasons for hospital pathology overutilisation from the perspective of the JMO. Methods A qualitative method, using focus group methodology, was undertaken. Sixteen JMOs from two hospitals participated in three focus groups. Data were analysed using thematic analysis. Results Three major themes contributed to overutilisation: the real and perceived expectations of senior colleagues, the level of JMO clinical experience and strategies to manage JMO workload around clinical systems. Within these themes, 12 subthemes were identified. Conclusions Overutilisation of hospital pathology testing occurs when there are high social costs to JMOs for underordering, with little cost for overordering. Interventions should restore this balance through reframing overutilisation as both a costly and potentially harmful activity, promoting a supportive culture with regular senior guidance, and addressing clinical systems in which missed tests create an excessive workload. What is known about the topic? Mean overutilisation rates of pathology testing are reported to be as high as 44%. Although numerous studies have reported successful efforts to decrease hospital pathology overutilisation, no primary research was identified that examined the JMO perspective on this subject. What does this paper add? Clinical need is not the primary factor guiding the pathology-ordering decisions of junior practitioners; rather, medical team culture, limited JMO experience and systems factors have a significant role. What are the implications for practitioners? The social and behavioural determinants of pathology ordering must be considered to achieve appropriate pathology test utilisation. These include senior medical officer engagement, the guidance of JMOs and clinical workflows.