Individual herds may experience exceptionally high rates (~50%) of cystic ovary disease (COD) over a period of months. Determining the cause of these multifactorial episodes is not easy, but the following questions should be addressed: 1) Is the diagnosis accurate, ie, are the structures being identified as cysts really cysts? This can be established via second opinion diagnoses, determination of milk or plasma progesterone levels, ultrasound examination of the ovaries in suspected cases, observing ovarian changes and time of estrous activity after treatment with prostaglandin products, and/or improving diagnostic skills by continuing education. 2) Has the palpation examination schedule for the herd changed? Initiating routine postpartum examinations for all cows and increasing frequency of herd visits can result in an increased apparent incidence. 3) Has the herd incidence of periparturient complications and stress increased? Cows having problems around calving (such as twins, milk fever, dystocia, retained placenta, ketosis, etc) are much more likely to develop cysts. Attempts to reduce these complications are indicated. 4) Have herd genetics been considered? It is well accepted that ovarian cysts are more common in certain lines. 5) Has the nutritional program of the herd been evaluated? Nutritional problems are frequently implicated as a risk factor for COD. Proper nutritional management of dairy herds is always warranted. Monitoring the effects of the nutritional program via a body condition scoring program should be done as part of the effort to reduce ovarian cysts in problem herds. 6) Has management of cows around estrus changed? Social and environmental changes may cause stresses associated with COD.