We don't celebrate Halloween over here. It's a weird thing really, in some cities people do try to emulate the US version of Halloween, because it's fun for the kids, but generally it's disliked and frowned upon. At most you'll see small neighbourhoods where people make an agreement to participate, but it's kept very confined, primarily for the safety of the children and also, as I've said before - not many are willing to participate to begin with. It's a foreign influence and it's considered unsafe and most people just don't want to see it.
Basically, in pre-christian times we held a festival of the dead, which people call our version of Halloween (except they're not similar at all, so I've no idea why), then in XII century it became integrated into the catholic Allhallowtide. So as a nation, officially we only celebrate the Allhallowtide, but there are remote regions which still perform some variations of the original, pre-christian tradition and the neo-pagan movement came up with something that they call "The day of the Ancestors", which is loosely based on our original pagan beliefs.
Didn't expect a history lesson, did ya?
TL;DR: We don't.