Amy Winehouse's parents Mitch and Janis were expected in court on Wednesday for the opening of an inquest to establish why the late singer died.
An initial post-mortem proved inconclusive.
But her family released a statement after receiving the results of toxicology tests.
"Toxicology results returned to the Winehouse family by authorities have confirmed that there were no illegal substances in Amy's system at the time of her death," said their spokesman.
"Results indicate that alcohol was present but it cannot be determined as yet if it played a role in her death."
Her father Mitch has said he suspects the star died after suffering while detoxing from alcohol and "there was nobody there to rescue her".
He said traces of the prescription drug Librium showed up in the toxicology report.
It is used to fight anxiety and withdrawal symptoms.
Amy passed away in July at the age of 27.
Photo: © Rex