Building materials supplier Grafton saw net income fall to €46.4 million or 20.1 cents a share for the first six months of its latest fiscal year.
This compares with net income of €92.6 million or 37.6 cents a share for the same period a year ago.
Pre-tax profits fell by 50 per cent to €53.4 million. Adjusted earnings per share were down by 47 per cent to 20.6 cent.
The company said that the first half of the year brought the "most challenging" trading condition encountered by the Group since the early 1990s. It said the impact of these conditions, together with a 13 per cent decline in sterling's exchange rate against the euro, resulted in "a significant reduction" in profitability compared to the first half of last year.
The company said trading conditions in July and August remained challenging and "there are no immediate signs of an improvement in our markets."
Sales for the firm, which is the country's largest supplier of building materials, fell 11 per cent during the first six months of the year to €1.44 billion.
Operating profit (before intangible amortisation) was down by 41 per cent to €72.9 million.
Irish turnover declined by 16 per cent to €530.5 million versus €628.8 million a year ago and operating profit was down 60 per cent to €24.3 million compared to €60.6 million in 2007.
Turnover fell by 16 per cent to €354.7 million in the group's merchanting business while a decline in consumer confidence impacted on the firm's DIY stores with turnover falling 16 per cent to €520 million and profits falling by 60 per cent to €24.3 million.
Grafton recorded a 8 per cent decline in turnover for its retailing division which includes the Woodies chain.
Turnover totalled €154.6 million compared to €168.2 million for the same six month period a yeara go and profitability was significantly lower.
In the UK, turnover declined by 7.4 per cent to €907.4 million compared to €979.4 million in 2007 but was up by 6.5 per cent in sterling. UK operating profit declined by 24 per cent to €48.6 million versus €63.8 million a year ago and by 13 per cent in sterling.