Jockey Jason Maskiell has appealed the severity of a lengthy ban for a failed drug test.

Maskiell pleaded guilty and was suspended from race riding by for 18 months last Friday after testing positive to a banned substance at Kyneton races on November 6.

The substance was not named by Racing Victoria stewards.

As part of the penalty, Maskiell is also banned from riding trackwork or barrier trials for 12 months.

Victorian Jockeys' Association chief executive Des O'Keeffe encouraged Maskiell to appeal the severity of the penalty.

"I think the penalty could have been structured a little bit differently so as to give Jason a greater incentive to do the work required to beat the demons that he's facing from time to time," O'Keeffe told Melbourne's RSN Radio.

It is the second time in just over two years Maskiell has been suspended for testing positive to a banned substance.