The presence of certain mycotoxins within poultry feed has a negative impact upon the growth and the quality of the final product in the form of meat and eggs. More than 300 different chemically diverse mycotoxins have been identified, but ochratoxins and aflatoxins are considered to be most harmful to the poultry industry. Ochratoxin, more importantly ochratoxin A (OTA) is produced by different species of Aspergillus and Penicillium spp. which are present as storage fungi within the stored grains and feed ingredients. Body weight gain has been found to decrease in a dose dependent manner when infected at rates of 0.5-29.4 mg/kg for 7-60 days in different experimental studies. Decreased feed intake has been observed at levels of 0.5-4 mg/kg OTA fed for 21-60 days, while egg production, hatchability, eggshell thickness and egg mass production is severely affected when 0.5-4 mg/kg OTA in feed was fed for 28-84 days. However, 0.5-20 mg/kg OTA given for between two and 10 weeks of age was sufficient to produce histopathological alterations in the liver, kidney, thymus, bursa of Fabricius, spleen, lungs and heart. The research shows that OTA adversely affects every organ in birds and, in the following review, OTA associated alterations in growth parameters, production performance and histopathological disturbances of different body organs are discussed.