A bus carrying volunteer doctors from La Paz towards the north of Bolivia crashed leaving 14 dead and 21 injured, the La Paz local government said on Monday.
The doctors were part of the MedFund foundation based in La Paz and were heading to five villages in the region around Apolo to the north of La Paz.
According to reports, the bus fell into a ravine on Sunday night close to Charazani, around 250 kilometers (150 miles) to the north of La Paz.
Amongst the dead were 11 woman, according to Daniel Quelca, the health service co-ordinator for the Apolobamba region.
Bolivia has a sorry record when it comes to highway safety, and crashes involving buses travelling at night are common.
The worst accident this year came in April when 25 people died when a head-on collision between two vehicles sent a bus crashing into a ravine to the north of La Paz.
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In February, 24 people died in an accident between a bus and a truck in Oruro.
And in January, 34 people died over a weekend in two separate incidents, the first a collision between two buses on the road between the southern regions of Oruro and Potosi, and the second when a bus careered over a cliff edge near the capital Sucre, in the center-south of the country.
Bolivia's authorities have shown little appetite to tackle the problem, with President Evo Morales writing on Twitter after the April accident: "To our brother drivers we ask you to always be very careful.