Purpose: The Cow's Milk-related Symptom Score (CoMiSS™), which considers crying, regurgitation, stools, skin and respiratory symptoms, was developed as an awareness tool for evaluating cow's milk-related symptoms. The scoring ranges from 0 to 33. A score ≥12 was proposed as being likely cow's milk-related and suggestive of allergy to cow's milk. This study aimed to determine the age-related CoMiSS™ values in presumed healthy infants in Poland. Methods: This was a cross-sectional study conducted in well-child clinics in two locations. Parents of the presumed healthy infants aged ≤6 months were approached during a routine checkup/vaccination visit. The exclusion criteria were as follows: presence of acute or chronic diseases, preterm delivery, treatment with therapeutic formula, and use of any food supplements (except vitamins) or medications. Results: Data from 226 infants were obtained (median age [Q1-Q3], 4 months [3-4]). The overall median (Q1-Q3) and mean (standard deviation) CoMiSS™ values were 4 (2-7) and 4.7 (3.5), respectively. The 95th percentile was 11. Scores on some, albeit not all, components of the CoMiSS™ significantly differed between age groups (crying, stools) or feeding type groups (stools and skin symptoms). Eleven children (4.9%) scored ≥12. Conclusion: This study adds to earlier age-related CoMiSS™ data by providing CoMiSS™ values in presumed healthy infants in Poland.