Poland's agriculture ministry said its routine sampling procedure had found a further case of mad cow disease in the country's Lodz province.
Veterinary authorities said they had begun investigating how the cow became infected.
The news shows how BSE, known in full as Bovine Spongiform Encepalopathy, continues to be a thorn in Poland's side as it works to improve food safety and quality standards.
Recent figures from the World Organisation for Animal Health, show that cases of BSE in Poland have been increasing over the last few years. The country reported no outbreaks between 1989 and 2000, but cases have crept up from four in 2001 to 19 last year.
The figures also found BSE cases rising, albeit on a small scale, in the Czech Republic and Slovakia. The Czech Republic confirmed eight cases last year, compared to two in 2001.
The trend is something food safety watchdogs in Eastern Europe will be wary of amid reports of dramatic drops in BSE cases elsewhere in the world.
The number of BSE-infected cows fell by 50 per cent in 2005 compared to 2004, according to the Food and Agriculture Organisation (FAO) of the United Nations, which worked closely with the World Organisation for Animal Health to compile its report.
The FAO said just 474 animals died of BSE around the world, compared with 878 in 2004 and 1,646 in 2003, and against a peak of several tens of thousands in 1992.
"It is quite clear that BSE is declining and that the measures introduced to stop the disease are effective," stated Andrew Speedy, an FAO animal production expert. "But further success depends on our continuing to apply those measures worldwide."
European consumption of beef has slowly been rising as public fears have diminished. For the first time in 20 years consumption of beef and veal surpassed EU production in 2003 and is expected to grow further by 2012, according to a recent forecast report by the European Commission.