Aim: Aldehyde dehydrogenase 1 family member A1 (ALDH1A1) is a putative cancer stem cell marker. This meta-analysis evaluated ALDH1A1 expression’s clinicopathological associations with lung cancer (LC), colorectal cancer (CRC) and breast cancer (BC). Materials & methods: Publications were retrieved from various databases and assessed for relevance and quality. Relationships between ALDH1A1 expression and clinicopathological characteristics were evaluated using Review Manager 5.2 software. Results: Thirty-eight studies were included (6057 patients). ALDH1A1 expression was significantly associated with the presence of LC; lymph node metastasis, clinical stage and differentiation in LC and BC; and molecular subtype in BC (p < 0.05). There were no significant association with BC tumor size and CRC. Conclusion: ALDH1A1 may be a stem cell marker in LC and BC.