Transcribing notes from meetings, making corrections to reports and returning phone calls at work are tasks that take enough time without having to decipher a co-worker's illegible handwriting on top of it. Use these strategies to help read the words even when the person isn't around to help you translate them.
Find words through out the text that you're able to read. If you know the context of the message or report, you may be able to piece one of his thoughts together that will lead you to the next and the next until you've translated the entire piece.
Search for letters in some words that you can recognize. Jot the letter above the illegible handwriting each time you spot it. Continue solving the "puzzle" one letter at a time until you can form enough words and sentences to understand the meaning.
Look through your co-workers office or through your old files to find any of his notes completed with neater penmanship. Although the piece you're trying to decode is messier, you may be able to match up enough words to read key phrases.
Seek help from another co-worker who works with the person more often than you do. She may be familiar with his handwriting and be able to decipher a few key sentences to give you the gist of the text.
If you find yourself dealing with your co-worker's illegible penmanship often, bring it to his attention by politely asking him to translate each time he writes you a note. If you always decipher it on your own, he'll never realize how much extra work he's costing you.