The full results for this won't be ready until Sunday 25 May. However, voting closed on the evening of Thursday 22 May and exit polls usually give a good indication of election results.
Judging by these UKIp (the United Kingdom Independence Party) will make the biggest gains and may even end up with twice as many seats as was predicted. The other big winner is the main opposition party, Labour, but although in actual numbers they will considerably increase their share of the vote (probably by about 200 seats) this is actually less than was expected, and a lot less than they need in order to be clearly the most popular party. The Conservatives and their Liberal Democrat partners look like losing a lot of support, while support for the Greens may grow much more than expected.
Of course, Euro elections are very different from national or even council elections, but all parties are watching these results with interest.