The aim of this study was the evaluation of animal health recording data based on veterinary diagnostic data subject to documentation by law from the year 2009. Based on this, the occurence of diagnosed cattle diseases in the Middle Weser Area was assessed. Analysis was performed for each age category milk cows, heifers and calves. Data was provided by three veterinary practices and included 8919 medicamental treatments on 118 cattle farms. First treatments against 29 different cow-, 23 heifer- and 18 calf-diseases were documented. Besides the single consideration of each documented diagnose, diagnoses were pooled into groups ot diagnoses for each age category. The three most common groups allowed a good insight into the diagnosed and treated diseases. In dairy cows, the diagnoses group of udder disases was predominant (31.0%), followed by diseases of the locomotion tract (25.4%) and antiparasitic treatments and prophylaxis (19.6%). In heifers, the diagnoses group of antiparasitic treatments and prophylaxis ranged at first place (83.2%), followed by respiratory diseases (6.1%) and diseases of the locomotion tract (4.6%). In calves, most medicaments were used for the treatment against respiratory diseases (54.7%), gut diseases (30.8%) and fungal skin infections (7.7%). Even though the informative value of veterinary diagnostic data has to be regarded critically, this study provided a clear picture of the most frequently diagnosed and treated diseases in cattle. Especially in the current discussion about the prudent use of veterinary medicaments, such analyses enable insights into animal health and conclusions on the amount of administered treatments without additional data acquisition. In due critical consideration of the disadvantages of such data, they can form the background of a digital documentation and integration of animal health information.