Only a few studies reveal immunological changes in breast milk after the intake of probiotic and none focus on secretory IgA (sIgA). The aim our report was to investigate the levels of sIgA in human breast milk and stools before and after 4 weeks of probiotic intake in a patient with ulcerative colitis (UC) and a control. The study included 2 lactating women: 1 with UC and 1 control. Both received daily 3.75 billion viable Lactobacillus bulgaricus for 28 days. SIgA was measured in breast milk and stools before and after the probiotic intake. The concentration of sIgA in breast milk before the probiotic intake in UC was 408.5 vs 137.4 µg/ml in contol. Fecal sIgA in UC was 420 vs 274 µg/ml in control. After 28 days of probiotic intake there was a decrease in breast milk sIgA in UC but an increase in control - 266.7 vs 914 µg/ml respectively. There was an increase in fecal sIgA both in UC and control - 674.4 vs 1033 µg/ml. It is tempting to speculate that the different sIgA secretion towards the probiotic may be a result of an altered mucosal immune response in UC.