The aim of investigations was to assess the occurrence of Elaphostrongylus cervi in Poland. They were conducted in thirteen forest inspectorates in eight voivodeships. Faeces were collected in winter, by following the traces of red deer on fresh snow. In total, 97 samples of faeces were examined. Five-gram samples were placed in a Baermann apparatus for 24 hours in room temperature. Then the extensiveness of invasion and the number of E. cervi larvae were determined under a binocular microscope. First stage larvae of E. cervi were found in all forest inspectorates examined. The extensiveness of E. cervi invasion in Zwierzyniec, Lubartow, Lutowiska, Tuchola, and Bytnica inspectorates ranged from 75% to 100%. The number of larvae in five-gram samples of faeces from different forest inspectorates varied from 1 to 848. As a result of these investigations, E. cervi was discovered in 13 new locations, all over the country, which proves that this parasitosis is common in all areas of Poland inhabited by red deer. The extensiveness of infection in the forest inspectorates examined was very high. In 11 out of the 13 inspectorates examined, it exceeded 80%, and in five it reached 100%. The mean number of larvae per 5 grams of faeces was also very high, exceeding 100 in 5 inspectorates. The present research confirmed the occurrence of E. cervi nematodes in 13 new areas. The results of this study, together with previous investigations conducted in Poland, demonstrate that the elaphostrongylosis of red deer in widespread all over the country. This parasitosis may also be dangerous for domestic ruminants grazed in forest pastures used by deer.