Wineries in the South West believe microbreweries are "diluting" the region's brand and threatening its status as WA's premier wine region.
There are eight breweries between Busselton and Margaret River and a ninth - the Batch Brewery House - opens early next year on Bussell Highway.
Cullen Wines managing director Vanya Cullen said it was a waste to build breweries on premium vineyard land.
"You would not see breweries in the middle of Burgundy or Bordeaux," Ms Cullen said.
"It's a dilution of the wine industry, which the Margaret River region is known for internationally and it is not seen favourably."
She hoped the wine industry would remain the major attraction to the region. "But who knows, breweries might take over - there's so many of them," she said.
Ms Cullen fears the region's newest kid on the block - Cheeky Monkey Brewery and Cidery - which opened next door to Cullen Wines last year, will cause cross-contamination between cultured beer yeast and wine yeast.
"This business will always be at risk because of that brewery," she said.
Brookwood Estate owner Trevor Mann, whose winery is flanked by Colonial Brewery and Cowaramup Brewery, said breweries were taking business from winery restaurants and cellar doors.
"The breweries are having a profound effect," Mr Mann said.
Cheeky Monkey director Brent Burton said breweries complemented wineries and did not compete with them.
"We are probably bringing business to the region and helping the wineries," Mr Burton said.
There was a "slight risk" of cross-contamination, but he said it was not high enough to warrant concern and he had a strict management plan to stop yeast escaping.
Batch Brewery House director Aaron Brown said the region had to diversify amid dwindling visitor numbers.
"In hospitality, everything has to change now and again to attract a wider variety of people who want a cheaper, more family friendly option," he said.
Sandalford Wines chief executive Grant Brinklow said breweries were not overshadowing wineries but they needed to offer premium products to preserve Margaret River's brand and not attract "adult schoolies".
Geographe Bay Tourism chief executive Simon Taylor said the breweries were helping wineries by attracting more visitors.
"A diverse product mix gives visitors more reasons to come to the region and encourages repeat visits," he said.
"The wine industry is world renowned and has certainly put the region on the map (but) we also have an exciting food scene and the emergence of craft breweries is providing another facet to this experience."