A heartfelt letter a young James Franco wrote to apologise for throwing eggs at his neighbour's home has surfaced online, 21 years after the incident.

The 127 Hours star was 14 when he was caught behaving badly in his Palo Alto, California hometown and he later expressed his remorse by penning a note to his neighbour, Dr. Michael Phillips Moskowitz.

Moskowitz let the teenager off the hook for the messy prank, but he saved the message and has now shared it on his men's shopping website, BureauofTrade.com, listing it as "priceless".

In the letter, Franco, who was known as Ted at the time, wrote, "Dear Dr. Moskowitz, First of all I will apologize once again for distroying (sic) your personal property. I did it out of carelessness, not thinking that feelings might be hurt. And valuable time and money wasted. It will never enter my mind to do something like this ever again.

"Thank you for being so graceious (sic) about this whole matter, and not haveing (sic) the police involved. It was very considerate of you to do that for us after we were discourtious (sic) to you.

"I am truly sorry. I hope you can just forget all this and put it behind us. I have learned my lesson. Thank you, Ted Franco".