This paper examines the characterisation of neural stem cells for oestrogen in vitro. Stroke is a problem for the ageing population. The ageing population is increasing but there is no licensed therapy for chronic stages of the disease. Stem cells are already known to have enormous potential to improve stroke outcome in the chronic stages1 but we need to improve their integration in vivo. Evidence also suggests that the female hormone, oestrogen, enhances differentiation of neural stem cells.2 The long-term aim of the present study is to determine whether oestrogen can improve the success of neural stem cell grafting in experimental stroke. We used an immortalised temperature sensitive murine neural stem cell line, the Maudsley hippocampal stem cell line clone 36 (MHP36) because they proliferate only at low temperatures (33°C) in vitro, develop into mature neurons and glia on transplantation into the higher temperature brain (37°C) and cease dividing once matured reducing the chance of producing tumours. The short-term aim was to fully characterise the MHP36 for oestrogen receptors (ER) and the enzyme, aromatase, which synthesizes oestrogen.