Lex Eisenhardt is one of Europe's foremost experts on early guitars, like the Vihuela, the Baroque- and Romantic guitars. He currently teaches both classical guitar and historical plucked instruments at the Conservatory of Amsterdam.

He has been a soloist in the Holland Early Music Festival in Utrecht. He also has given concerts in the Early Music network, both as a soloist and together with soprano Maria-Luz Alvarez. He was invited for concerts and classes throughout Europe, the United States and Australia. He has made extensive study of the vihuela literature and playing technique, as well as of the very specific technique of the baroque guitar. As a result he made recordings of vihuela works by the sixteenth century Spanish composer Luys de Narvaez and several with music for the baroque guitar (see discography).

Lex Eisenhardt has also made recordings of music by Fernando Sor on an original period instrument.