Although there has been increasing data on pediatric anaphylaxis, information about anaphylaxis in the 1st year of life is scarce. This study provides detailed information on clinical signs and symptoms of anaphylaxis in the 1st year of life. A retrospective review was performed of our pediatric allergy database between 2007 and 2011. Children who met the diagnostic criteria of anaphylaxis were included. They were categorized as "infant" if they were <= 12 months of age at the time of anaphylactic reaction and "children" if >12 months. There were 104 patients (60 male and 44 female subjects) who met the diagnosis criteria of anaphylaxis. From the 104 cases of anaphylaxis, 23 (22.1%) were infants. Boys (p = 0.043), atopic eczema (p = 0.049), and history of food allergy (p < 0.001) were significantly higher in infants than in children with anaphylaxis. Severe anaphylaxis was less frequent in infants than in children (p = 0.04). There was no significant difference between infants and children considering cutaneous and respiratory symptoms (p > 0.05 for both) but persistent vomiting was (p = 0.023). Irritability, persistent crying, and somnolence are the signs which are difficult to interpret in infants with anaphylaxis. Within these signs, irritability, persistent crying, and somnolence were present in 69.6, 43.5, and 26.1% of infants, respectively. Blood pressure was measured in 5 infants (21.7%) compared with 44 children (54.3%; p = 0.005). Four children (4.9%) required more than one epinephrine treatment, but no infant did. Median observation periods were 4 hours in both groups (p = 0.087) and no biphasic reactions occurred in either. Food (p < 0.001) was significantly more and drugs (p = 0.015) were a less frequent cause of anaphylaxis in infants than in children. Anaphylaxis in infants is not rare but many signs of anaphylaxis are overlooked and still undertreated.