I explain how arbitrary correlators of string theory in the Euclidean AdS3 can be computed from the correlators of Liouville theory. This makes use of the KZ-BPZ correspondence, which relates on the one hand the Knizhnik-Zamolodchikov equations reflecting the group symmetry in AdS3, on the other hand the Belavin-Polyakov-Zamolodchikov equations reflecting the presence of degenerate fields in the Liouville correlators.