OK, I will post the solution. Don't read on if you want to try it on your own.

Some think that the friend's age has to be specified, but that is exactly what makes the puzzle interesting!

First of all, the fact that YOU don't know the friend's age doesn't mean that he himself doesn't know it.

Therefore, if, after clue #2 he doesn't have enough information, that means that he has to be 36 years old, since only for 36 years there is more than one possibility: 6,6,1 and 9,2,2 (some of you have listed all the combination in other messages in this thread). For any other age, he would have only one possibility.

The third clue eliminates the combination 6,6,1: the man has ONE oldest son, not twins.

Therefore, the ages are 9,2,2.

>A man says to his friend:
>
>"I have three sons; I want you to figure out their ages from the following clues:
>
>1) The sum of their ages is 13.
>
>2) The product of their ages is the same as your age."
>
>"Well, I would need more clues than that."
>
>"OK, here is the third clue: my oldest son went to visit our neighbors' children."
>
>"OK, now I have enough clues."
>
>What are the ages?