The talk will describe the results of a research project to investigate the problems young women physics researchers encountered during early stages of their careers and their perceptions of the longer-term difficulties they anticipated were they to pursue a career in physics research. The project examined quantitative data from a large sample of female members of the UK Institute of Physics (IOP) and qualitative data from intensive interviews with 27 young female doctoral and post-doctoral researchers at an early stage in their careers. In the survey of women PhD members of the IOP, only 15% of the younger women (aged under 30) said they had encountered gender barriers compared with 45% of older women. However, within a few years of completing their PhDs only 25% of the young women remained in physics research although they had previously aspired to work in this area. The reasons given for leaving physics included a dislike of the male culture or atmosphere in research labs, the fact that few of the young women thought that they would ever attain a senior physics post, concerns about balancing a research career with raising a young family and anticipating a need to relocate to match a partners career moves. These are clearly gender-related barriers and constraints although these young women often did not perceive them in this way. This research examines the notion of direct and indirect gender barriers. It addresses the idea of subtle discrimination by examining both institutional employment practices and the prevalent male culture or atmosphere in physics research, which contribute to the leaky pipeline in womens physics employment in the UK