Objectives: To assess changes in senior management culture in English NHS hospitals between 2001 and 2008. Design: Longitudinal study comprising cross-sectional surveys of board levels managers at three time-points using a validated culture measurement instrument - the Competing Values Framework. Setting: English NHS hospital trusts. Main outcomes: There has been a decline in 'Clan' and an increase in more competitive 'Rational' cultures among senior management teams in NHS hospital trusts during the period 2001-2008. Conclusions: Government policy for the NHS has espoused the desirability of competition, particularly since 2002. Our data suggest that corresponding changes in the cultures of senior management teams in NHS hospital trusts is beginning to occur, with the expectation that these organizations will pursue more competitive strategies.