"I'm confident that I'm sane," he tells Time magazine in its Oct. 18 issue, on newsstands Monday. "I don't get delusions and so forth.
"I had very serious problems with social adjustment in adolescence. ... But it would have to be distinguished between an organic illness, like schizophrenia."
The interview coincides with the imminent release of Kaczynski's book Truth Versus Lies, published by Context Books.
Kaczynski was sentenced in 1998 to life without parole for conducting an anti-technology bombing campaign that killed three people and injured 22. He pleaded guilty to avoid a trial at which his lawyer had planned to offer an insanity defense. But the guilty plea also saved him from being sentenced to the death penalty.
Asked about the prospect of spending life in prison, the former Montana forest recluse says he is not optimistic about life in general. "I do not want to live long. I would rather get the death penalty than spend the rest of my life in prison," he said.
Kaczyinski also spoke about his brother, who turned him in to authorities. When asked what he would say to his brother, David, Kaczynski replies: "I would just turn my back and wouldn't talk to him."
He says if their roles had been reversed, and he had suspected David of being the Unabomber, "I would have kept it to myself."