Stock Spirits total revenues declined to €108m during the six months ended 30 June 2015 from €137.7m over the same period last year.
The spirits producer's performance is adversely affected by the ongoing market disruption in Poland.
The company's operating profit before exceptional costs accounted to €5.2m, down from last year's €23.2m.
According to the company, the total vodka market in Poland reduced by 2.7% during the period, showing a slowdown in the trend when compared to 3.6% during the same period last year.
Stock Spirits CEO Chris Heath said: "As reported at the time of our AGM in May, the disruption in the supply chain and aggressive competitor pricing in Poland following the excise tax increase in January 2014, resulted in a very poor first quarter for the Group.
"Trading in Poland improved significantly in the second quarter, but not enough to fully offset the poor first quarter. All other markets have traded in line with our expectations. Therefore as expected, the Group's overall results for the first half of the year 2015 have been disappointing."
