Médecins Sans Frontières was there at the start of the current Ebola outbreak in west Africa and has played a pivotal role in the global response—building health centres, training care staff, and even advising the United Nations, writes Sophie Arie. The charity has decades of experience in bringing volunteer doctors to where they are needed in emergency situations and for longer term humanitarian projects. This is why The BMJ has chosen MSF for its winter charity appeal this year. Please give generously