BACKGROUND AND OBJECTIVE: An infant's age at introduction of complementary solids may contribute to food allergy. We aimed to synthesize the literature on the association between age at introduction of complementary solids, excluding milk products, and food allergy and sensitization. DESIGN: We searched the electronic databases PubMed and EMBASE (January 1946-February 2017) using solid food, allergy and sensitization terms. METHODS: Two authors selected papers according to inclusion criteria, identifying 16 cohort studies, 1 case-control study and 8 randomized controlled trials (RCTs). Pooled effects across studies were estimated using random-effects meta-analysis. RESULTS: Cohort studies - Introducing complementary solids at age ≥4 months versus <4 months was not associated with food allergy (OR 1.22; 95%CI, 0.76-1.96) but was associated with food sensitization (OR 1.93; 95%CI 1.57-2.38). First exposure from age 4-6 months versus <4 months was not associated with food allergy (OR 1.01; 95%CI, 0.64-1.60) but was associated with food sensitization (OR 2.46; 95%CI 1.55-3.86). RCTs - Egg exposure from age 4 months was associated with reduced egg allergy (OR 0.63, 95%CI, 0.44-0.90) and sensitization (OR 0.76, 95%CI, 0.51-0.95). Peanut exposure from age 4 months compared to delayed exposure was associated with reduced peanut allergy (OR 0.28, 95%CI 0.14-0.57). CONCLUSIONS: We found no evidence from observational studies that introducing solids before 4 months protected against food allergy, but there was evidence for protection against food sensitization. From RCTs, introducing egg from 4-6 months and peanut from 4-11 months, reduced the risk of egg allergy, peanut allergy and egg sensitization. This article is protected by copyright. All rights reserved.