Vienna's Leopold Museum says that after taking his clothes off, the man calmly sauntered through the exhibition, dressing again only after a security guard asked him to do so.
Museum spokesman Klaus Pokorny said Tuesday that the museum had nothing to do with Saturday's strip, describing it as a "spontaneous act." He says other visitors did not appear disturbed.
He said that since its Oct. 19 opening, the "Nude Men" exhibition had attracted more than 65,000 visitors - all of them dressed except for one.