Rains have failed in West, East and Southern Africa, leaving up to 15m facing starvation, according to international aid agencies.
The World Food Programme and aid agencies have launched appeals for hundreds of millions of dollars to provide food to the hungry and try to avert a humanitarian disaster.
BBC News Online lists some of the main aid agencies working in the region and gives details of how to donate to their appeals.
Disasters Emergency Committee (DEC)
Donations to UK charities, including many of those listed below, can be made via DEC, which has a report on the famine. Donations can be made online or by calling +44 870 6060900.
The World Food Programme has its own website where you can find out how you can make donations to their famine appeal for Southern Africa and Ethiopia.
Oxfam International has a briefing paper on the famine. Donations can be made via the Oxfam sites in each individual country.
In the UK, contributions are accepted via Oxfam GB's special Southern Africa and Ethiopia donations pages, or by post at Oxfam, 274 Banbury Road, Oxford, OX2 7DZ, UK. Tel: +44 1865 313131
UNICEF UK has launched its Southern Africa Children's Appeal to help the most vulnerable children across the region. You can also make credit card donations for work in Ethiopia and Southern Africa by phone on the 24 hour hotline 44 (0) 8457 312 312 or send cheques payable to UNICEF to UNICEF's Southern Africa Children's Appeal, FREEPOST, Chelmsford, CM2 8BR.
International Federation of the Red Cross
The International Federation of Red Cross and Red Crescent Societies has launched appeals to help those affected in both the Horn and Southern Africa.
Donations can be made online
World Vision is also active in Southern Africa. In addition to its main website, the charity has more information on its national sites - the UK site has further details specific to the UK.
Care International has up-to-date information on the famine, especially in Malawi. It is possible to donate online.
CARE International UK is also accepting donations at CIUK, 10-13 Rushworth Street, London SE1 0RB, UK
British-based charity Christian Aid has produced a special report on the situation. You can donate online to Christian Aid's appeal, or by post to: Christian Aid, PO Box 100, London SE1 7RT, UK. Tel: +44 80 80 004 004
Save the Children
The UK arm of Save the Children has information on its appeal relating to the Malawi famine, and opportunities to donate.
Medecins sans Frontieres
This international charity providing emergency medical care has a special report on MSF's involvement in emergency relief in Angola, as well as a donations page, with details on how to donate from different countries. In the USA, the charity is called Doctors without borders.
The international charity World Relief has a special report on the Southern African famine.
Dublin-based Concern is doing emergency work in several parts of Angola and Ethiopia. Donations can be made via the web-site.
The relief and development agency Tearfund has launched an appeal to help ease the devastating food crisis in southern Africa and has reports on its webpages about the situation in Ethiopia.
Donations to the Tearfund Southern Africa Crisis Appeal can be made via the web-site - or in the UK by credit card by calling 0845 355 8355 (local rate calls) - or sending a cheque to Tearfund Southern Africa Crisis Appeal, Freepost, Teddington, Middlesex, TW11 8BR. Cheques should be payable to Tearfund and earmarked for "Southern Africa Crisis".
Action Against Hunger
The relief and development charity Action Against Hunger is carrying out an emergency nutrition programme in Malawi. Information about the famine in Ethiopia and Southern Africa can be found on the Action Against Hunger website. Donations to the Action Against Hunger Africa Appeal can be made online or by phone 08705 100 722.
The Catholic Agency for Overseas Development has launched an appeal for the southern African famine. In Zimbabwe it is already carrying out a large-scale feeding programme and it is helping partners in Zambia and Malawi to do the same. CAFOD is also working in Mozambique and Angola. It is on standby to help with relief work in Ethiopia and Eritrea. The hotline number for donations is 0500 85 88 85.
The Irish aid agency GOAL is responding to humanitarian emergencies in Malawi, Angola, Ethiopia, Sudan and Democratic Republic of Congo. Donations can be made online or by calling GOAL UK at +44 207 6313196, GOAL Northern Ireland at 028 9075777 or GOAL Ireland at 353 1 2809779
The World Health Organisation has launched an appeal to fund the provision of basic health services across southern Africa for particularly vulnerable groups in parallel with the distribution of food aid. Details of this and its reports on the famine in Ethiopia are on the website.