Abstract: Objective To explore differently expressed microRNAs between basal and Luminal A subtype of breast cancers and study the regulatory roles of these microRNAs. Methods A dataset of microRNAs expression profilings of basal and Luminal A subtype of breast cancers was obtained from GEO database and analyzed by BRB-ArrayTolls. Target gene sets were collected by prediction software TargetScan, miRDB and TarBase. And then Gene Ontology categories and pathways of target gene sets were further analyzed by DAVID database. Results Up-regulation of 31 microRNAs and down-regulation of 23 microRNAs were identified in basal compared with Luminal A breast cancers (P≤0.001). Correspondingly, two gene sets of 4 916 and 3 217 target genes were collected. Further Gene Ontology analyses showed that different Gene Ontology categories were enriched between two target gene sets. There were 35 and 39 KEGG pathways (P≤0.05) were enriched separately in two target gene sets. Also, 5 and 9 BIOCARTA pathways were enriched (P≤0.05). Conclusion There are different microRNAs expression patterns between Basal and Luminal A breast cancers.Function analysis indicated that differently expressed microRNAs may take partin quite different biological processes and signaling pathways, and may have different regulating roles in different breast cancers.