Mastitis is the most common disease of dairy cows and the most expensive in terms of treatment. For this reason, great emphasis must be placed on its prevention. Based on literature sources, it can be said that there is a positive correlation between the prevalence of udder edema and the occurrence of mastitis. Our studies were carried out in a dairy farm in Csongrád-Csanád county. So far we have collected data from 64 cows with udder edema. The severity of udder edema was evaluated on a scale of 0–3 points one week before calving and for 3 weeks after calving. We observed that udder edema occurred in 78% of the studied cows at the time of the first calving. After calving, the length and diameter of the four udder teats were examined. Both anterior and posterior teats were shortened in severely edematous cows. When examining the diameter of the teat, we found that, depending on the severity of the edema, the anterior and posterior udder teats were 2.5 and 1.6 and 1.6 and 1.5 mm thicker respectively than those of cows without edema.