Objective To explore Vietnamese obstetricians' experiences and views on the role of obstetric ultrasound in clinical management of complicated pregnancy and in situations where maternal and fetal health interests conflict. Design Seventeen obstetricians in northern Vietnam were interviewed as part of the CROss-Country Ultrasound Study (CROCUS) project in 2013. Data were analysed using qualitative content analysis. Results The participants described ultrasound as a central tool in prenatal care, although they called for increased training and resources to prevent inappropriate management. A prevailing overuse driven by women's request and increased commercialisation was described. Other clinical examinations were seen as being disregarded by women in favour of ultrasound, resulting in missed opportunities for identifying potential pregnancy complications. The use of ultrasound for sex selection purposes raised concern among participants. Visualisation of human features or heartbeat during ultrasound was commonly described as the point where the fetus became regarded as a 'person'. Women were said to prioritise fetal health interests over their own health, particularly if a woman had difficulties becoming pregnant or had undergone assisted fertilisation. The woman's husband and his family were described as having an important role in decision-making in situations of maternal and fetal health conflicts. Conclusions This study provides insight into issues surrounding ultrasound use in contemporary Vietnam, some of which may be specific to this low-income context. It is clear that ultrasound has become a central tool in prenatal care in Vietnam and that it has also been embraced by women. However, there seems to be a need to balance women's demands for obstetric ultrasound with better recognition of the valuable contribution to be made by the full range of clinical examinations in pregnancy, along with a more strategic allocation of resources, that is, use of obstetric ultrasound based on clinical indications. Better regulation of private obstetric practice also appears to be needed. While the root causes of sex selection need to be addressed at societal level, efforts are also required more immediately to find ways to combat the inappropriate use of ultrasound for the purpose of sex selection.