US dollar or Euro cash or travellers checks may be changed into local currency at airports and banks. Small denomination notes are best (US $1, $5, $10, and $20) as change is often not available for larger notes. Always keep your receipt so that when you depart you may change your money back to US dollars or Euros.
Please note that the majority of establishments, banks and money changers in Kenya and Tanzania no longer accept US dollar currency of any denomination printed before the year 2000. Some establishments have recently been known to only accept notes printed after 2003.