Sussex is fourth in a list of counties with the most country homes for sale.
The average price of a top country house has more than trebled during the past ten years, say researchers.
A large period house or spacious modern residence now costs about £2 million, compared with about £600,000 in 1992, according to the Country Life Elite Property Index.
The index is based on properties advertised in Country Life magazine, considered one of the key places to advertise a high-value house by estate agents.
According to the magazine, Devon had the most houses advertised last year, knocking Oxfordshire into second place.
Hampshire remained the county with the third largest number of homes for sale, followed by Sussex and Surrey.
The most popular type of property remained classic manor houses, particularly Elizabethan, Queen Anne and Georgian, followed by old rectories and vicarages, farmhouses and cottages.
Gregory Pickard, an associate with Strutt and Parker in Lewes, said there had been a sharp growth in country house prices in Mid Sussex.
He said: "There has been a huge increase. In three years we have seen it rise by about ten to 15 per cent a year."
Peter George, of Eric Marchant Estate Agents in Hassocks, said there was a shortage of good quality country homes in Mid Sussex as it was a very popular area.
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