The aim of the present study was to determine the mycobiota and natural levels of mycotoxins such as zearalenone, fumonisin B(1), aflatoxin B(1) and ochratoxin A present in raw materials and finished fattening pig feed. Samples were examined for total fungi and genera distribution. Zearalenone, FB(1), AFB(1) and OTA contamination were determined using high pressure liquid chromatography and thin layer chromatography. Milled maize and finished feed samples showed fungal contamination over than 1 × 10(4) CFU/g. All samples contained at least one of the main mycotoxigenic genera Aspergillus, Fusarium and Penicillium. A. flavus and F. verticillioides were the most prevalent species. Only some Aspergillus section Nigri strains from suckling pig to growing pig samples were able to produce OTA. A. flavus strains from milled maize, wheat bran, suckling pig to growing pig samples were able to produce AFB(1). All samples were positive for FB(1). Sucking pig, piglet, growing and boar feed samples showed ZEA natural contamination. AFB(1) and OTA contamination were not detected. There was a 100% correlation between FB(1) and ZEA contamination in sucking pig, piglet, growing and boar feed samples; 50% piglet samples and 67% suckling pig samples showed ZEA levels over the recommended limits. The present study has shown the occurrence of two mycotoxins, FB(1) and ZEA in feed intended for fattening pig consumption. In animal production, the simultaneous presence of toxicogenic fungi and low dietary levels of mycotoxins in field conditions can cause possible health impacts and lost performance in pigs from feeding spoiled feeds.