"We know the integrity of what we have done and regulators have looked at it," Holmes said during an interview with Wall Street Journal global technology editor Jonathan Krim.
The Journal released a statement standing by its report, which raised questions about whether the Silicon Valley-based startup was delivering as promised when it came to tests done from blood drawn by simple pin pricks.
The newspaper accused Theranos of using nothing more revolutionary than widely available commercial equipment.
"Nothing said at the conference by Ms. Holmes refutes the accuracy of the reporting done by John Carreyrou or of the articles," the Journal said.
"The Journal reiterates that our articles about Theranos were thoroughly reported, fair and wholly accurate."
Holmes maintained otherwise during the on-stage interview, contending that concerns about Theranos testing methodology in the report were "completely false."
"We know what we are doing and are very proud of it, using finger prick testing and trying to expand the universe of how many tests are available," Holmes said.
Theranos has been cleared by US regulators for one kind of blood test as part of a procedural strategy to expand the line-up of tests from there, according to Holmes.
She said Theranos has done more than 3.5 million blood tests.
Theranos is among Silicon Valley unicorns -- private startups with valuations of a billion dollars or more based on money pumped in by investors.
The startup, which ironically operates in a building that was occupied for decades by The Wall Street Journal in the city of Palo Alto, has recently been valued at about $9 billion.
Theranos boasted of being able to do blood tests faster, more economically, and with only a tiny finger prick instead of needing vials of blood.
Theranos is continuing its work under the watchful eyes of regulators, according to its chief.
"Just because some guy reports false stuff about us doesn`t mean it changes our business," Holmes said.
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