You can just walk in. But if you tell them you're on TRT, they'll send you away. You'll have to get a "script" from your TRT doctor and then you work with the Special Donations division w/in the Red Cross. It's not a pain in the ass once you've set it up, but it takes a bit to do that. The script is for 1 year so you can pretty much go when you want after you're in the system. There are others that just walk into the Red Cross and donate. I'm a sucker for certain rules so I told them and got the script.