The Maccabeats and TV star Mayim Bialik have teamed up to help raise money for a bone marrow charity.
They are hoping to raise $80,000 - $10,000 for every night of Chanucah – to support the work of the Gift of Life Bone Marrow Foundation, which works to find donor matches for people who need transplants.
The Maccabeats, whose Chanucah-themed 1a>Candlelight1b> video attracted nearly six million hits on YouTube last December, have launched the campaign with another festive tune.
They have filmed a cover version of the song 2a>Miracle2b> by the Orthodox hip hop artist Matisyahu, with the aim of using their musical notoriety to attract donors.
They have been joined in their efforts by Ms Bialik, famous in the 1990s for playing Blossom in the series of the same name. She now stars in the cult series The Big Bang Theory.
To help encourage fans to dig deep, they are offering money-can't-buy prizes including a spot in the next Maccabeats video and a phone call with Ms Bialik.
Ms Bialik, whose children appear alongside her in the Miracle video, said she was very excited to work with The Maccabeats.
"I believe in the world seeing a new kind of Orthodoxy through groups like The Maccabeats," she wrote on her blog. "Their message is lovely, their intention is good, and they are smart and fun.
"Being a part of a video by a group that I respect and adore is sort of insanely surreal; I feel like the girl in the Dancing in the Dark Bruce Springsteen video who's pulled up on stage to dance with him during the concert - except The Maccabeats can't touch me to pull me up on stage, can't watch a woman dance, and would never wear a red bandana around their kippah-adorned heads."