You can dye synthetic hair. I'm a cosmetologist. I wouldn't suggest it because the color of the extensions are dyed that color. And supposed to be that color. So, if you wanted to dye them. You would have to go through the same process as if they were your real hair. Stripping, bleaching, (if they are the color blonde you would like to use go ahead and dye the color if not....) bleaching again, (wait a couple of months before doing that though) and then get it to the color that your wanting to dye it. The reason why you shouldn't do that. Is because you can dry the extensions out and the hair will be dead. When you wash it, it will be hard to brush. It'l be dead hair. And there would be nothing to do about it. BUT sometimes that doesn't happen. It's really just your choice.