The main objective of this study was to describe in detail the pathoanatomical and histopathological lesions found in the kidneys of three calves with bilateral suppurative pyelonephritis. The disease was observed for the first time in southeastern Bulgaria on a family cattle farm. The farm consisted of 48 adult Holstein cattle and 21 newborn and growing calves aged from 24 hours after birth to 45 days. The calves were born in the mothers' pens and then independently sucked colostrum. In the winter, within 72 hours, 5 calves fell ill and died: four females and one male, aged 5 to 9 days, with signs of dehydration, refusal of food and water, frequent and painful urination, pyuria, hematuria, kyphosis and fever. No treatment was given and no other calves in the group showed clinical signs. Three calf carcasses were submitted for necropsy and subsequent diagnostic testing by the farmer himself. After necropsy of the calves, tissue samples from the kidneys for histopathological examination. Samples of parenchymal organs (lung, liver, spleen and kidney), blood from the heart and a ligated section of the small intestine were also used for bacteriological studies. In conclusion, suppurative pyelonephritis is a rare multifactorial disease in newborn and growing calves with bacterial etiology. The macro- and microlesional changes in the kidneys of three calves described in the presented report will be of great benefit to veterinarians and researchers in the diagnosis, differential diagnosis and treatment of kidney diseases in ruminants.