Objectives: The study intended to analyse the characteristic shedding pattern of Staphylococcus (S.) aureusin subclinically mastitic quarter foremilk samples and to improve the detection rate of this pathogen by modifying the methods of analysis. Material and methods: Quarter foremilk samples from cows with known S. aureus infections were drawn repeatedly and cultured for S. aureus in two trials. In trial 1 (T1), 25 quarters of 25 cows known to be infected with S. aureus were sampled at five consecutive days at second milking time before milking took place. In trial 2 (T2), 12 animals were sampled also on quarter foremilk level before and after a stressing incident (claw trimming). All samples of both trials were analysed for S. aureus in parallel using two methods, i. e., regular culturing on sheep blood agar with aesculin as recommended by the German Veterinary Association ("DVG"; corresponds largely to IDF recommendations), and a commercial, ready-to-use agar system (Petrifilm™ Staph Express). Results: In T1 S. aureus was detected successfully and quantitatively in 24 and 120 out of 125 samples using the DVG and Petrifilm methods, respectively. 82% of samples positive for S. aureus yielded bacterial counts of < 100 cfu/ml. If only the DVG method was applied, six out of 25 animals examined would not have been detected as shedders of S. aureus. In T2 S. aureus was confirmed in three out of 12 animals (using the DVG method) before the claw trimming. After stress the amount of correctly identified animals rose to 11, increasing the bacterial count significantly (p < 0.002) at the same time. Conclusion and clinical relevance: S. aureus is shed frequently by infected quarters in very small numbers. The cultural proof on blood agar often fails as small inocula (0.01 ml) per quarter or even mixed samples of all four quarters are applied onto the agar. False-negative findings may challenge the success of udder health sanitation measure. The odds to detect udder quarters infected with S. aureus properly increase when more inoculum is used for culturing and when sampling is repeated at short intervals. Sampling the cows after stressing also improves the detection rate of infected animals.