From Michael Nielsen:
How many of Einstein’s 300 plus papers were peer reviewed? According to the physicist and historian of science Daniel Kennefick, it may well be that only a single paper of Einstein’s was ever subject to peer review. That was a paper about gravitational waves, jointly authored with Nathan Rosen, and submitted to the journal Physical Review in 1936. The Physical Review had at that time recently introduced a peer review system. It wasn’t always used, but when the editor wanted a second opinion on a submission, he would send it out for review. The Einstein-Rosen paper was sent out for review, and came back with a (correct, as it turned out) negative report. Einstein’s indignant reply to the editor is amusing to modern scientific sensibilities, and suggests someone quite unfamiliar with peer review:
We (Mr. Rosen and I) had sent you our manuscript for publication and had not authorized you to show it to specialists before it is printed. I see no reason to address the in any case erroneous comments of your anonymous expert. On the basis of this incident I prefer to publish the paper elsewhere.
P.S. Mr. Rosen, who has left for the Soviet Union, has authorized me to represent him in this matter.
Wow. And there is more in the post, especially regarding how comparatively recent peer-review became a formal practice.