Travel insurers paid out £275m for travellers' emergency medical care last year, according to the ABI.
ABI figures also show that the cost of medical expenses claims soared by 270% in the last six years.
Medical treatment is now the biggest claims area for travel insurers at 55% of all paid claims, up from 33% six years ago.
Travel insurers dealt with around 337,000 claims for emergency medical care last year, the figures show.
Stomach upsets, ear infections, allergies and heart problems are the most common illnesses needing medical treatment while abroad.
Claims dealt with by insurers include::
•£86,000 to cover the cost of treating a holidaymaker who suffered a massive heart attack and needed to be flown home via air ambulance to the UK.
•£54,000 to treat a holidaymaker who was diagnosed with bipolar disorder while holidaying in the USA and then needed to be flown back to the UK with a doctor escort.
•£20,000 to cover the cost of treating a man who had a heart infection and brain haemorrhage. Costs included treatment at two hospitals and an air ambulance back to the UK from Spain.
•£11,000 to treat a holidaymaker who suffered a broken arm after a fall in Spain.
ABI director of general insurance and health Nick Starling said: “The biggest cost if something goes wrong on your holiday will not be a lost passport, delayed flight or stolen camera, it will be the medical treatment that may be needed if you, or someone in your family, gets hurt or falls ill. Medical costs abroad can run into tens of thousands of pounds which makes travel insurance absolutely essential."