So, who wrote this immortal Hippocratic oath: Hippocrates or one of his Hippocratic followers?

Though no-one knows for certain, the answer is potentially neither.

The most compelling evidence for this argument is that the ideals expressed in the oath do not reflect those in works genuinely attributed to Hippocrates.

Ludwig Edelstein was a professor at Johns Hopkins during the early 20th century and a primary contributor to the understanding of Hippocratic works.