Microbiol dysbiosis and antibiotic exposure have been implicated in the pathogenesis of pediatric inflammatory diseases.To investigate the impacts of infantile infection and antibiotic exposure on pediatric psoriasis development METHODS: This is a nationwide nested case control study. From the National Health Insurance Research Database of Taiwan, a total of 1,527 patients with pediatric psoriasis were identified and matched with 15,270 reference subjects without psoriasis, for the period 2000-2017. Demographic characteristics and comorbidities were compared. Conditional stepwise logistic regression analysis was conducted to examine the associations.The mean ages were 9.9±3.7 years in both groups. Atopic dermatitis (adjusted odds ratio [aOR] 2.07, 95% confidence interval [CI] 1.84-2.32) and family history of psoriasis, especially of the mother (aOR 9.86, 95% CI 6.89-14.10) or other first-degree relatives (aOR 5.49, 95% CI 3.91-7.70), were independently associated with pediatric psoriasis on multivariate analyses. Skin viral and bacterial infections (aOR 1.35, 95% CI 1.13-1.62) and fungal infections (aOR 1.71, 95% CI 1.44-2.04) in the first 2 years of life were significantly associated with pediatric psoriasis. Systemic antibiotics exposure was not. These results were consistent at different time periods across sensitivity analyses.Information about diet and lifestyle was not available.Skin infections at an early age were associated with pediatric psoriasis development.