Falling cider sales in the UK has been blamed by Cantrell & Cochrane (C&C) for the lay-off of 70 workers at the Bulmers plant in Clonmel, Co Tipperary.
Notice will be served to the workers next week, and the redundancies will take place over the next month.
The company recently completed a programme to increase capacity at the Clonmel plant and took on 190 workers over the past 12 months.
A spokesman for C&C said the company was hopeful that it would increase numbers again when trading conditions improved.
C&C told the stock market that the wet summer weather meant sales of Magners, the brand name for Bulmers in the United Kingdom, would be at least 15 per cent below forecast.
Shares in C&C fell after the company said its profit growth this year would be flat and first-half operating profit down by around 35 per cent.
The share price had fallen back at the start of the year after a mooted takeover fell through, though it has stabilised in recent days.
The company said it would maintain its marketing investment levels but cut costs elsewhere.
"This was a prudent business decision on the back of current trading conditions which are due to the wet weather over the summer months," the spokesman said.
Chief executive Maurice Pratt said he expected "more normal conditions" to prevail in 2008. He predicted Magners sales would increase over the longer term as the new brand gained greater recognition and became regarded as more than a summer drink.