Background: Cow's milk protein allergy (CMPA): The topic of definition still causes confusion among physicians. Words such as “allergy," “intolerance," and “hypersensitivity" are used interchangeably. The accepted definition of allergy is “a hypersensitivity reaction triggered by specific immunologic mechanisms". There is no such thing as “allergy to lactose" but rather lactose intolerance. The authors introduced the acronym “CoMiSS" (cow's milk-related symptom score). Objective: To evaluate CoMiSS in children with cow's milk allergy at Pediatric Department, Faculty of Medicine, Zagazig University. Patients and Methods: This study was conducted during the period from December 2018 to May 2020.  Cow's milk-related symptom score was assessed. Results:  There was statistically significant increase in eosinophilic count among confirmed CMA than no CMA. There was statistically significant higher total score of CoMiSS among confirmed CMA than no CMA, and another one regarding each symptom of CoMiSS score. Accuracy of CoMiSS in diagnosis of CMA was 90.8%. The percentage was for sensitivity (86.4%), specificity (93.4%), positive predictive value (88.3%) when the score is >12 and negative predictive value (92.2%). Conclusion: CoMiSS is a simple, fast, and easy-to-use tool to raise awareness and help in early diagnosis of CMPA, but hard to handle with many of illiterate mothers. CoMiSS is a helpful tool and applicable method to screen for CMPA, though there may be risk of under-diagnosis when CoMiSS≥12 is used as the criterion for early pick-up of CMPA in Egyptian infants.