This study analysed three acute phase proteins in milk from natural cases of bovine mastitis and compared their profiles across different pathogens causing the infection. Their ability to differentiate subclinical and clinical mastitis from normal (uninfected) milk samples was also examined. Samples from various dairy farms across Scotland submitted to the Veterinary Diagnostic Services unit of the University of Glasgow were used for this study. They were subjected to microbiological examination for mastitis pathogens, evaluation of somatic cell counts and analyses by ELISAs for haptoglobin, C-reactive protein and mammary associated serum amyloid A3. Each acute phase protein (APP) was compared across pathogens and form of mastitis. Significant differences (P = 0.000) were observed for each APP between causative pathogen and form of mastitis. There were significant correlations between the pathogen and the form of mastitis and the 3 APP showed similar profile for the different pathogen type and forms of mastitis. It can be concluded that the aetiological pathogen of mastitis to a large extent influences the clinical form of the disease, this, ultimately being reflected in the degree and course of secretions of the acute phase proteins; Hp, M-SAA3 and CRP into milk during mastitis. Variations of which, show correspondent patterns with related pathogen/form-of-mastitis.