Hi Tony, I checked java.util.Random several years ago, and at that time it was really bad - somewhat slow and with obviously periodic behavior. I would not be surprised if Sun had fixed it since then, but it still lacks utilities like generating vectors of random numbers, which makes it effectively slow for many applications. - Dima. > I completely agree with Norman that the java.util.Random class is the best thing to use. > > I don't know of any studies that show how good a random number generator java.util.Random is, I would guess that it is good enough for anything we are doing right now. If anyone has the time/interest it might be useful to compare it with the random number generators in the colt package > > http://www-itg.lbl.gov/~hoschek/colt/api/cern/jet/random/engine/package-summary.html > > which claim to be very good and fast. > > Tony >