Half of winter sports enthusiasts have been involved in a collision or near miss, and three-quarters of them needed to claim for a medical bill, according to Aviva.
Yet, the insurer says 15% of those skiing, snowboarding or tobogganing this winter won't have appropriate cover.
Despite the high accident rate on the slopes, almost half of those going without insurance don't think they need it, while a third wrongly believe that having a European Health Insurance Card (EHIC) is enough, and one in ten simply forget to buy it.
However, when the insurer asked if they could afford the medical treatment they might need, two-thirds said they couldn't.
The most the average respondent said they could pay was just under £500, while the typical winter sports claim last year was actually £740: a shortfall of almost £250.
Heather Smith, Aviva's director of general insurance, said: "We never like to think about the worst-case scenario, especially when going on holiday, but when it comes to winter sports this can be a costly error.
"Even if you consider yourself to be a competent skier, remember that mishaps can happen to anyone, and the cost of even a minor accident can run to hundreds of pounds."
The insurer says the average cost of treating spinal cord damage is £31,000, knee damage £24,000, a dislocated ankle £22,000 and a leg fracture £16,000.
Anyone travelling to Switzerland, Norway, Liechtenstein, Iceland or an EU member country needs an EHIC to access the same medical treatment as a resident.
The cards, which are free, last for five years and every member of a group, including children, requires one.
To apply on behalf of the whole family, log on to EHIC.org.uk or call 0300 330 1350.
But remember that not all countries have a free health service, so there could still be a charge for basic care.
And, wherever you are holidaying, the EHIC doesn't cover private treatment, costs such as mountain rescue, or replacing lost or stolen property.
This means it should never be seen as a substitute for a comprehensive travel policy with winter sports cover.
Tom Bishop, Direct Line's head of travel insurance, said: "Winter sports injuries can be very costly, and even when treated in a hospital which accepts the EHIC, a skier could face thousands of pounds in charges for mountain rescue, ambulances, new flights and additional accommodation.
"For example, a helicopter piste rescue to a local hospital will typically cost around £2,000, and if you need to be brought home from an Alpine resort by stretcher on a commercial flight, or on an air ambulance, this can cost at least £10,000. This is why taking out appropriate travel insurance is so crucial."
However, winter sports policies vary hugely, with a wide range of exclusions and different levels of cover, so it is vital to check the small print.
Moneysupermarket.com says a family of four going on a week-long skiing holiday in Europe can insure themselves for £21.14 with insurefor.com, which offers £10 million of medical cover, £750 for personal baggage and £350 for ski equipment with excesses of £150 for each.
But for just £11 more, the same family could have £15m of medical cover, £1500 of baggage cover and £1000 for ski equipment, with excesses of only £100, from provider Cover for You.
Regular travellers often find that taking out an annual policy, which provides protection for a year's worth of trips and includes winter sports cover, is more cost effective than individual ones. Moneysupermarket recommends all travellers choose a policy offering at least £2m of cover for medical expenses, £1mn personal liability, £3000 for cancellation - or enough to meet the total holiday cost - £1500 for baggage and £250 for cash, with excesses of no more than £100.
Meanwhile, Direct Line is urging all skiers and snowboarders to wear approved safety helmets. Research for the insurer found that skiers wearing helmets experience at least two-thirds less G-force in a crash than those without, greatly reducing their risk of serious head injury.
Direct Line says in a 20kph collision an unprotected head experiences a force of nearly two tonnes, potentially causing significant damage, while a crash at 30kph without a helmet could be fatal.
Mr Bishop added: "We deal with around 3000 winter sports claims per year, the majority of which will be medical, and unfortunately three or four of these per year will be fatalities. Even one fatality is one too many."
To reduce your chances of being badly hurt on the slopes, wear suitable eye protection and an EN 1077 approved ski helmet that fits well and is in good condition. Check bindings are correctly set for your weight, skiing style and speed, and always match speed and terrain to your ability.
Don't go off alone, be aware of your surroundings and other skiers around you, and always carry a piste map, mobile phone or suitable radio and a list of local emergency numbers.