The Ukulele Orchestra of Great Britain (UOGB) said their reputation could be tarnished by the German-based United Kingdom Ukulele Orchestra (UKUO).
The UOGB had sought a High Court injunction against the rival group of British players ahead of the UKUO's upcoming UK tour.
But the judge ruled in favour of the UKUO, saying it was not in competition.
Judge Richard Hacon agreed that, as the group had been performing in Germany for some years, the UOGB should have acted sooner.
Both orchestras perform their take on contemporary pop songs.
The UOGB, whose members dress like a traditional orchestra and sing and tell jokes on stage, have been performing for more than 25 years, released records and have appeared on television.
The British group took action ahead of the UKUO's first UK tour, which begins on 15 October in Lincoln.
"We have issued proceedings against a German-based musical group for registered trademark infringement. However the court didn't grant the injunction," UOGB founder George Hinchliffe told the BBC at the London court.
He added: "It's really not a policy of ours to comment upon litigation while it's still going through the courts. And we're a bit busy at the moment as we're just about to start a tour of China."
The court heard the UKUO performed in English and had a "certain English humour" which was aimed at the continental market and Germany in particular.
"We are very pleased with the outcome," said Peter Moss, UKUO musical director.
"Our view has always been that we never, ever wanted to have competition with the other side. We wish them well. We hope people will now come to see us play."
The UOGB said they was considering further legal action to protect their "name and reputation".
A British ukulele group has lost its trademark infringement battle against a rival band over its name.