We evaluated the farmer-recorded data on the incidence of selected diseases in 111,197 Holstein cows from 603 herds in the Czech Republic. The incidence of diseases was expressed as the lactational incidence Li = (number of affected lactations / number of lactations) x 100. We found that 52.53 % of recorded lactations were affected by some of the defined diseases. The reproduction disorders were the most frequent (Li = 29.20 %), followed with udder diseases (22.34 %), the foot and claw diseases (12.89 %) and the digestive trackt and metabolic diseases (6.68 %). The clinical mastitis (20.78 %), the metritis (14.56 %) and the cystic ovaries syndrome (13.12 %) were the most frequent of partial diseases. Some farmers fail to report all diseases, when most of them send the data on udder diseases (95.85 % of herds), while the digestive tract and metabolic diseases were reported fewer (63.52 %). The incidence of most diseases grew with the order of lactation. The data on health events recorded by farmers represent the valuable source of information, and they are usable, after careful editing, for the genetic editing, for the genetic evaluation of health traits in the Czech dairy cattle.