We evaluated conformation traits related to udder health traits in Holstein cows. The relationships among exterior, the incidence of clinical mastitis and somatic cell score were analysed in Czech Holstein cattle. Effect levels for somatic cell scores were estimated by the linear animal model. The logistic regression model was used for clinical mastitis analysis. The scoring of conformation traits was on a nine-point scale. Clinical mastitis was considered an all-or-none trait with 0 (no clinical mastitis case) and 1 (at least one clinical mastitis case). The incidence of clinical mastitis was monitored in seven lactation periods of 50 days and for the whole lactation. Somatic cell count was monitored in 10 periods of 30 days and for the whole lactation and transformed to score. The source of data was a national recording in the Czech Republic. The cases of clinical mastitis from 27,709 first lactations of 17,622 cows were recorded on 15 farms for 17 years. Pedigree involved 24,499 animals. It was strong and tight Fore Udder Attachment, intermediate and shallower Udder Depth, high Rear Udder Height, deep Central Ligament, intermediate Udder Width, Middle of quarter Front Teat Placement, intermediate Teat Length, midpoint Rear Teat Placement, and intermediate Body Condition Score. The incidence of clinical mastitis and somatic cell score significantly decreased with decreasing udder depth. Shallow udders were associated with the lowest incidence of clinical mastitis and somatic cell score. Cows with udders below the hook had the highest incidence of clinical mastitis and somatic cell score. Clinical mastitis can be included in the selection program as a new trait in the Czech Republic. This step will be preceded by national monitoring of clinical mastitis prevalence on farms. The recorded data could be used to estimate breeding values for clinical mastitis resistance.