A number of studies have suggested that early life exposure to antibiotics can lead to an increased risk of developing eczema. This systematic review and meta-analysis of observational studies, involving children or young adults aged 0–25 years, assessed the impact of antibiotic exposure either in utero or during the first 12 months of life on subsequent eczema risk. Twenty studies examined the association between prenatal and/or postnatal exposure to antibiotics and development of eczema. The pooled odds ratio (OR) for the 17 studies examining postnatal antibiotic exposure was 1·41 [95% confidence interval (CI) 1·30–1·53]. The pooled OR for the 10 longitudinal studies was 1·40 (95% CI 1·19–1·64), compared with a pooled OR of 1·43 (95% CI 1·36–1·51) for the seven cross-sectional studies. There was a significant dose–response association, suggesting a 7% increase in the risk of eczema for each additional antibiotic course received during the first year of life [pooled OR 1·07 (95% CI 1·02–1·11)]. Finally, the pooled OR for the four studies relating to antenatal exposure was 1·30 (95% CI 0·86–1·95). We conclude that exposure to antibiotics in the first year of life, but not prenatally, is more common in children with eczema.