British Airways lost more luggage than any other major European airline last year, figures have shown.
About 5.6 million items were mishandled by the AEA airlines.
For every 1,000 passengers carried by BA in 2006, 23 bags went missing according to data from the Association of European Airlines (AEA).
The UK's Air Transport Users Council (AUC) which released the figures said BA had admitted its performance was not good enough and had apologised.
Across the 24 largest airlines, more than 5.6 million bags went missing.
This is an average of 15.7 bags per 1,000 travellers.
About 85% of missing bags were returned to their owners within 48 hours, the AEA said, but it added that some "never get returned at all".
'Stress and inconvenience'
German carrier Lufthansa, Italy's Alitalia and Air France were among those with worse-than-average records.
Some airlines which are members of the AEA, including Virgin Atlantic and BMI, do not release lost luggage figures and nor do no-frills airlines such as Ryanair and Easyjet.
The AUC said that mishandled baggage could cause passengers "considerable stress, inconvenience and expense" and that its data showed some struggled to get "reasonable redress".
"When passengers hand over their suitcases at check-in, they should be able to expect to see them at the other end," said AUC chairman Tina Tietjen.
In comments to the AUC, BA's operations director, Geoff Want said that increased security since last August's terror alert combined with the growing volume of luggage being handled at Heathrow "had not helped" its performances.
"We accept that overall the levels of service we offered to our customers has not been up to an acceptable standard," Mr Want said.
"We fully apologise to customers who have been affected by delayed baggage in the last year."