The Commission has no plans to visit the country as part of its grocery inquiry - despite holding personal hearings in Scotland in September and in Northern Ireland next week (see left).
The Farmers' Union of Wales, which made a written submission to the investigation in June, called on the inquiry team to travel to Wales.
"We are disappointed the Commission isn't coming to sense the effect the increasing power of supermarkets is having on agricultural Wales," said Arwyn Owen, FUW director of policy. "In a country such as this the consequences are far reaching. Farmers need clear signals there is a future for them. At the moment there are no clear signs. If the Commission did come to Wales it would see how vulnerable some producers are."
Alun Fredd, assembly member for Plaid Cymru, said he was "surprised and disappointed" the inquiry team was not coming.
"Two abbatoirs have closed recently in north west Wales which caused a great deal of worry for the farming community. There's no doubt one of the prime reasons was the effect of the supermarkets." But the Competition Commission insisted it would hold hearings in Wales if there was sufficient demand.
"It's not out of the question we will go to Wales but at the moment nothing has been scheduled," a spokesman said. "We have had lots of responses from Northern Ireland and Scotland but we haven't had quite the same response from Wales.
"Part of the reason may be the way things are set up. For example there's an NFU in Scotland and Ulster but the NFU for England also covers Wales and we have already met them.
"We have made it clear we want to hear from everyone. We want to cover all of the UK, but we can't just pitch up in Wales without anyone to see."