Background: Faulty Complementary feeding (CF) is a worldwide problem that increases risk of malnutrition, gastrointestinal, respiratory illness, childhood obesity, allergic manifestation, and immune system disorders. Aim: to investigate the impact of faulty practices of complementary feeding on growth parameters, and to focus on the common adverse effect. Subjects and Methods: Our study is a cross sectional study that was carried out in Outpatient Clinics of Pediatrics at hospitals and health care units in the Suez Canal area. A well-designed Questionnaire was done to show the pattern of CF of 418 infants below 2 years selected in sequence. Infants with positive family history of allergy, congenital anomalies, debilitating systemic disease and infants under treatment were excluded from the study. We did a 20 minute interviews with mothers of included infants to answer a questionnaire about the dietetic history. Anthropometric measures and full examination were done for every infant. Results: Our results showed that the incidence of faulty CF was (58.7%), mothers who introduced complementary feeding before 4months was (47.5%), their infants were more exposed to gastrointestinal illness (52.2%), respiratory illness (76%), eczema (51.8%) and mouth ulcers (74.6%), than infants who started CF at the age 4-6months and after 6 months. Infants who started CF after 6months were more exposed to be underweight (43.2%) and to have manifestations of pallor and vitamin D deficiency (37%). Conclusion: Introduction of food before 4months leads to a significant higher incidence of gastrointestinal illness, eczema, respiratory illness, mouth ulcer, and obesity while, introduction of food after 6months lead to the risk of underweight and manifestations of pallor and vitamin D deficiency.