The repertory of versatile violinist Isabelle van Keulen includes many contemporary works as well as standard repertory. She often performs chamber music and sometimes plays the viola as well as the violin. In 1988, van Keulen made her recording debut as part of an octet led by violinist Gidon Kremer, performing Schubert's Octet in F major, D. 803. That was the first of many chamber recordings made by van Keulen, who often collaborated during the first part of her career with pianist Ronald Brautigam. She founded the Isos Quartet in 1995 and performed with that group as its first violinist. In 2023, she joined pianist Oliver Triendl for the album Grigory Frid: The Complete Works for Violin and Piano.