The International Dairy Federation's (IDF) criteria for classification of subclinical bovine health conditions does not provide a true picture of the health status of the udder. When combining these criteria with the serum albumin levels of milk samples, the IDF's classification of sub-clinical mastitis could be extended to include 8 possible conditions such as normal quarters, septic mastitis, aseptic mastitis, relevant and irrelevant teat canal infection, specific and unspecific hyperalbumingalactia and unspecific cellular reaction. When the bacteriological results of teat canal swab samples were combined with the IDF's standards, these conditions could be scaled down to 4 diagnoses which included normal quarters, aseptic mastitis, teat canal infections, subclinical mastitis and a combination of the latter 2 conditions. When applying the teat canal swabbing technique, up to 16% of quarters classified as normal and 10% as cases of aseptic mastitis according to the IDF's criteria in fact, have TCI. Since classification of the health status of quarters according to the IDF's criteria and with due regard to the bovine serum albumin values of milk, did not include the bacteriological results of the teat canal swab samples, further research must be done to clarify the existence of conditions in the IDF classification. Teat canal infections may result in damage to the udder parenchyma as manifested by the elevated bovine serum albumin content of milk.