This study looks into the impact of capital flows that have been prevalent in some SEACEN countries prior to the recent financial crisis and examines the effectiveness of monetary sterilisation. Empirical findings suggest that monetary sterilisation is the most important policy response in Indonesia Malaysia the Philippines and Thailand. Evidence also indicates that open market operations (OMO) as a form of monetary sterilisation has limits and while capital controls may be effective in certain circumstances such an option should only be temporary and implemented as a last resort.