Director general George Entwistle has defended the BBC's response to the Jimmy Savile sex abuse scandal, but accepted it raised questions of trust.
He told the Commons culture committee that since the "very, very grave" claims had emerged, "we have done much of what we should have done".
Mr Entwistle said he believed a "broader cultural problem" had existed within the BBC in the past.
This had allowed former presenter Savile to carry out his abuse, he said.
"There is no question that what Jimmy Savile did and the way the BBC behaved in the years - the culture and practices of the BBC seems to allow Jimmy Savile to do what he did - will raise questions of trust for us and reputation for us," he told the Commons culture, media and sport select committee.
"This is a gravely serious matter and one cannot look back at it with anything other than horror, frankly, that... his activities went on as long as they did undetected."
Police have described Savile, who was also a DJ and died last year aged 84, as a predatory sex offender, and believe he may have abused many people, including young girls, over a 40-year period.
A criminal investigation is under way.
Mr Entwistle said: "I'm not sure in the 60s and 70s... they [staff] would have felt there was anything they could do" about sexual harassment.
Nowadays BBC staff "know where to go" over harassment complaints, he added.
On Monday, BBC Panorama reported on the abuse allegations and an earlier BBC Newsnight investigation into Savile that was dropped last year.
Mr Entwistle said that, after seeing the Panorama broadcast, he believed the investigation by Newsnight into Savile should have been allowed to continue.
Mr Entwistle said the Panorama programme pointed to the BBC's health as a media organisation, rather than being a "symptom of chaos", because it showed the organisation's capacity to investigate itself.
He said no other news organisation in the world would do this.
Newsnight editor Peter Rippon has stepped aside amid an inquiry into why the programme dropped its investigation.
The director general said it was a matter of "regret and embarrassment" that Mr Rippon's original blog post about the dropping of the report had been inaccurate.
But he told MPs that he believed, "to the best of the evidence we have been able to assemble", the explanation now being offered by the BBC for the dropping of the Newsnight report was accurate.
Earlier this month, in a blog, Mr Rippon explained the editorial reasons behind his decision to axe the Newsnight report. He said it was "totally untrue" he had been ordered to do it by bosses as part of a BBC cover-up.
On Monday the BBC issued a correction to some specific elements of the blog, calling it "inaccurate or incomplete in some respects", although it did not suggest he had been put under pressure to drop the report.
Following the Panorama broadcast, a BBC statement added: "We should also make it clear we now accept that the Newsnight investigation did not start out as an investigation into the Surrey police's handling of the case against Mr Savile."