2 guides, each rated 1 to 5 with the reason — and two lists per place, where you are comfortable and where to pay attention. Nowhere is called dangerous; the specific thing is what helps.
Very safe town with almost no crime against visitors. The real hazards are elsewhere: medical care in Laos is poor and anything serious means evacuation to Thailand, so travel insurance with evacuation cover matters here more than almost anywhere. In rural areas outside town, stay on marked paths — unexploded ordnance from the 1960s and 70s is still being cleared.
Comfortable: Luang Prabang
Riding a scooter with no licence, which invalidates every travel policy in Laos
Kuang Si Falls — the upper pools, which are slippery and are where people fall
Bag snatching along the riverside path after the night market closes
The town has changed a great deal since the years when tubing and riverside bars killed tourists regularly; the worst of that was shut down after 2012 and it is a calmer place now. It is not risk-free: the river runs hard in the wet season, the caves flood, scooter injuries on gravel are routine, and drink safety at the remaining party spots deserves the same care as anywhere. Medical care is minimal — Vientiane is an hour away and Thailand beyond that.
Comfortable: Vang Vieng
Tubing after drinking, which is what the town was infamous for and is still how people drown
Cave and lagoon tours with no guide and no light
The buggy and quad tours, which are unregulated
The ratings are this site's own, from the guides' authors and the corrections readers send in; they are not an index. Read the general advice in travel safety tips.