One problem related to transmission fluid leaking has been reported for the 2000 Lexus RX300. The most recently reported issues are listed below.
2000 Rx300 transmission failure at approximately 121,000 miles . . . Dealer does not do rebuilds, so quoted for $4100 a new one without any detailed information on what exactly was wrong with it. Had it towed to reputable specialist, and was told a rebuild would cost more than a "re-manufacture" . . . $3600 + tax for 12 month warranty. Got it done, brought it home the 1st day and is leaking transmission fluid so need to bring back for a possible fix or swap. Not happy. No other mechanical issues with the car for the 7 years we've owned it.