Julián de Ajuriaguerra (b. 1911, Bilbao; d. 1993, Villefranque, France) was a major Basque scientist and one of the most important psychiatrists in contemporary history. He met Michaux in Paris and collaborated on his mescaline experiments by documenting and analyzing the effects of this substance on the artist.

Based on these experiences he wrote and published, together with F. Jaeggi, the essay Le poète Henri Michaux et les drogues hallucinogènes. Contribution à la connaissance des psychoses toxiques, expériences et découvertes du poète Henri Michaux (1963).