Top-class racehorse and stallion Naturalism has died at Meringo Stud on the NSW south coast aged 29.

"He retired from racing in 1993 and stood at Segenhoe Stud before relocating to Meringo Stud," Kylie Mercer from Meringo said.

"Naturalism served mares up until 2010 and had been enjoying his retirement at our stud.

"He was a favourite of all at Meringo Stud and we feel privileged to have looked after him.

"He was also a favourite of the Freedman brothers and they were here not long ago paying him a visit. He will be missed by all."

In a stellar career, Naturalism won three Group One races, the AJC Derby, Rosehill Guineas and Caulfield Stakes and another eight black-type races.

He fell in the 1992 Cox Plate but recovered to run a close second in the Japan Cup later that year.

Naturalism retired with 12 wins and 12 placings from 34 starts.

Lee Freedman rated Naturalism as one of the five best horses he ever trained.

"He was a brilliant horse and had the ability to run sensational sectionals," he said..

"He should have won Super Impose's Cox Plate in 1992 and probably his greatest performance was his second in the Japan Cup as he wasn't really a 2400 metre horse."

Freedman's trainer brother Richard posted a tribute on Twitter.

"I'm so sad to say that Naturalism - perhaps my favourite horse ever - died today at Meringo Stud. He was 29. I saw him only a month or two ago and he seemed so happy and vital. He was pound for pound the best horse I've laid a hand on. RIP old mate." he said.