Queensland stewards have charged 15 people, including 13 trainers, with buying unregistered substances after a state wide investigation over the past two months.

In a statement on Wednesday morning, the Queensland Racing Integrity Commission said it had informed 13 thoroughbred trainers, one stable hand and one jockey they had been charged with allegedly procuring substances or preparations in breach of the applicable legislation.

Those charged are trainers John Zielke, Jared Wehlow, Ricky Vale, Benjamin Williams, Christopher Tapiolas, Ian Shaw, Toni Schofield, Steven Royes, Kevin Miller, Darryl Hansen, Darryl Gardiner, Kristy Best, and Trinity Bannon, stablehand Andrew Minton and jockey Mark Barnham.

They are based in areas from the Sunshine Coast to central Queensland.

QRIC boss Ross Barnett said the alleged breaches were as a result of a state-wide investigation into the alleged procurement of substances or preparations in breach of Australian Rule of Racing 256(2)(a)(iii).

"The rule says: A person must not have in his or her possession or on his or her premises any medication, substance or preparation which has not been registered, labelled, prescribed, dispensed or obtained in accordance with applicable Commonwealth and State legislation," Barnett said.

"All those charged have been notified and Stewards have requested submissions in writing or at an Inquiry on a date to be fixed."

It is understood some of those charged face multiple offences while others face as few as one.

The charges relate to purchase or procuring substances but not administering, which is a more serious charge.

There have been several raids conducted by police on racing stables in Queensland this year but no information was available on whether Wednesday's charges were related to those investigations.