Objectives In the evaluation of children with Kawasaki disease (KD), the age of onset is important and complications may occur if the distinctive features are not assessed accordingly. The objective of the study is to define the clinical and laboratory presentations and treatment outcomes of KD in infants <= 6 months of age compared to those >6 months multicentrically. Methods This retrospective study reviewed the medical records of the patients diagnosed with KD and followed up between January 2009 and January 2019. Results A total of 204 KD patients were enrolled and grouped according to age as Group I (<= 6 months, n = 31) and Group II (>6 months, n = 173). Except for cervical adenopathy (19.3% vs. 47.4%, p = 0.03), the major clinical manifestations of KD were similar between groups I and II. However, the frequency of incomplete and atypical KD was higher in Group I (38.7% vs. 24.8%, p = 0.04, 38.7% vs. 8.1% p < 0.001, respectively). Clinical features such as vomiting/diarrhea (19.3% vs. 1.1% p < 0.001), aseptic meningitis (19.3% vs. 2.3%, p = 0.001) were more common in Group I. Percentage of neutrophils (45.5 vs. 36, p = 0.004) and hemoglobin levels (8 vs. 10.5 gr/dL, p = 0.02) were statistically lower and platelet count (737,000 vs 400,000/mm(3), p = 0.004) was statistically higher in group I. Coronary artery lesions (CALs) were more common in Group I (48% vs. 20%, p < 0.001). Harada and Kobayashi scores appear to be effective in predicting coronary artery lesions (CALs) and IVIG resistance in the entire cohort. There was no diagnostic delay in group I (5.5 vs 6.5 days, p = 0.88). Conclusions Since clinical presentations and laboratory features of KD may vary with age, and the frequency of atypical and incomplete presentations is high, awareness of KD in young children should be raised among pediatricians.