Thousands of hunt supporters have been out on the first day of hunting in England and Wales since the ban on hunting with dogs came into force.
Foxes were still being killed on Saturday
The Countryside Alliance called on hunt supporters to meet as normal, but vowed they would stay within the law.
Although hunting with dogs is now a criminal offence, exercising hounds, chasing a scent trail and flushing out foxes to be shot are still legal.
One anti-hunt protester was taken to hospital after a violent clash in Kent.
The man suffered facial injuries after an incident involving a group of men at the end of the East Kent Hunt, near Ashford.
In Wiltshire, police arrested four men under the new law suspected of hunting with dogs.
The group, from South Wales and Ireland, have been released on bail but police say they may face prosecution under new poaching laws.
It is believed more than 270 hunts went out on Saturday, just one day after the ban came in.
They were greeted by big crowds in many areas of the country, with actor Jeremy Irons and former minister Kate Hoey among the supporters.
Anti-hunt groups - such as the League Against Cruel Sports - deployed 100 monitors at hunts to check for illegal activity.
WAYS TO HUNT LEGALLY
Hunting rabbits or rats instead of foxes or hares
Using no more than two dogs to flush out a fox to be shot
Drag or trail hunting (using an artificial scent to hunt with hounds)
Using hounds to flush out a mammal to be hunted by a bird of prey
Exercising packs of hounds without using them to hunt
Using terriers to flush and shoot foxes, to protect gamebirds
Mike Hobday, from the league, said video evidence of the law being broken was to be passed onto police.
"Our evidence suggests that most hunts did operate within the law, many meeting and promptly going home and others peacefully exercising their hounds or drag hunting.
"However, we have received reports of what we believe is clearly illegal activity by a number of hunts across Britain."
BBC correspondent Simon Hall at Postbridge on Dartmoor in the West Country said 2,000 people had turned out to welcome the hunt.
'We will prevail'
And the BBC's Sarah Mukherjee, with the Beaufort Hunt in Badminton, Gloucestershire said several hundred people had gathered on foot to see the hunt, with 150 on horseback.
Tom Heap, BBC rural affairs correspondent, said it appeared that hunstman had, for now, been sticking to the new rules.
And while there was big turnout in support of the hunts on Saturday, he said it remains to be seen if the level of backing can be maintained.
Billy Vestey, four, took part in his local Hertfordshire hunt
Before riding out with the hunt, former minister Kate Hoey told crowds: "We will prevail and this law will have to be overturned."
Judith Moritz, in Melton Mowbray, said anti-hunt activists were out to monitor the four hunts operating in that part of Leicestershire, but were outnumbered by large crowds of followers.
The Countryside Alliance said the meets would show the new law was "impossibly difficult to determine" and open to different interpretations.
Chief executive Simon Hart said: "There has been hunting in England for 700 years. This [ban] may take two or three years, perhaps two or three months, to unpick.
"It will be nothing more than a temporary break in normal service, as broadcasters say."
Conservative family spokeswoman Theresa May said if the party was in government again it would make sure the law was repealed.
Suffolk Chief Constable Alastair McWhirter, the Association of Chief Police Officers' spokesman on rural policing, told the BBC the law would be enforced, although the police would not break up hunts.
The Attorney General Lord Goldsmith has so far not issued any instructions to police on how they should deal with any hunters who do violate the law.
He said he would consult the director of public prosecutions and the police "in the near future" to decide what measures to take on hunting prosecutions.