I know of no way you can transfer airline miles directly to MR points. There may be some indirect way, but I'm relatively sure it wouldn't be through Hilton

.
Addendum: There
is a way. If you convert your UA miles to Diners Club points, you can then convert the Diners Club points to MR points at a rate of 2500 Club Reward points equals 1500 MR points, see:
http://www.marriottrewards.com/point...sp#diners_club
Now, whether that's a good deal or not depends (as always) on what you want and what you've got. 200K MR points going this route would "cost" 333,333 United miles (at 10,000 United Mileage Plus miles = 10,000 Diners Club Reward points = 6,000 Marriott Reward points).
At 2 cents per mile, 333,333 miles is worth $6,666.66; are 5 nights at the Ritz worth that much? Of course, if you have more Mileage Plus miles than you'd ever use on flights, that would be another story.
And you also have the challenge of the purported 50,000 miles yearly limit on transfers from UA to Diners (although some say that's not enforced).
For comparison, 250K MR points would transfer into 100,000 UA miles.
[This message has been edited by Counsellor (edited 05-12-2002).]