Veteran Gosford trainer Fred Cowell has died aged 78 after a long illness.

Cowell had been based at Gosford for more than 30 years and trained a number of successful horses, highlighted most recently by Group winner Mighty Lucky.

"Fred Cowell was an absolute gentleman and a very popular figure in the NSW racing industry," Racing NSW chief executive Peter V'landys said.

"We are very saddened at his passing. Our thoughts are with his family and friends at this very sad time."

The Cowell-trained Uncle Sam ran in his name at Cessnock on Monday, finishing second.

Mighty Lucky's four stakes wins included the 2015 Group Three Summer Cup and he has won more than $850,000.

Cowell is survived by wife Irene, and his greater family and friends.