Background: Pathologic(p)stage I lung adenocarcinoma (LUAD) patients exhibit high levels of genetic heterogeneity and the association between the genomic characteristics of (p)stage I LUADs and tumor recurrence remains poorly understood. Circulating tumor DNA (ctDNA) monitoring after resection represents a useful tool to predict response to therapy and tumor recurrence but its application in (p)stage I LUAD patients remains controversial. In addition, it is of great clinical interest to decipher the difference of genetic features between ground-glass opacity (GGO) and solid nodules (non-GGO) subgroups. Methods: Tumor tissues and matched post-operative plasma samples were collected from a total of 86 Chinese (p)stage I LUAD patients who were enrolled in a clinical study (NCT03172156). Comprehensive genomic profiling was performed using capture-based hybrid next generation sequencing by targeting 422 cancer relevant genes. Results:EGFR and TP53 represent commonly mutated genes in this cohort of (p)stage I lung adenocarcinoma, followed by alterations in ALK, PIK3CA, STK11and MYC. For a median follow up period of 21.54 months after surgical resection, we observed that ctDNA positivity significantly correlated with an increased probability of early tumor recurrence or metastasis (P= 0.03, HR = 7.9), and in particular, the EGFR mutation status of ctDNA samples rather than that of primary tumor samples significantly correlated with shorter disease-free survival (DFS). Further comparison between GGO and non-GGO subgroups indicated that the frequency of TP53 mutations in non-GGO was markedly higher than that in GGO (48% vs 20%, P< 0.05). In addition, pathway analysis showed that the epigenetic regulation pathway was more frequently affected in the GGO subgroup, while impaired apoptosis/cell cycle pathway was more enriched in the non-GGO LUADs. Conclusions: Our data show that ctDNA positivity, including the EGFR mutation status, significantly correlated with early relapse or metastasis after surgery, representing a useful tool to predict treatment response and tumor relapse in (p)stage I LUAD patients. Mutated TP53 was more abundant in non-GGO comparing to GGO (p)stage I LUADs that may act as potential oncogenic driver in LUAD development and/or disease progression. Clinical trial information: NCT03172156.