From: Timothy Collinson
>
> She wanted to know what's the worst medical emergency they've had in
> terms of illness or accident and needing doctor etc.  anyone know?

If we don't limit ourselves to the ISS, there have been a number of fatal accidents (those in space involved life support failure) and a few more significant issues; http://en.wikipedia.org/wiki/Illness_and_injuries_during_spaceflight has a lot of things to look at.

Bear in mind that the total number of people who have ever been on the ISS is fairly low, so most uncommon problems might have just failed to appear at random.