Retinoblastoma (RB) is the most common intraocular malignant tumor in childhood. To investigate differential expression of microRNAs (miRNAs) in RB cell lines of different growth patterns: SNUOT-Rb1 with adherent and more rapid growth and Y79 with nonadherent and slower growth, miRNA microarray was performed. Common mRNA targets of each miRNA were extracted from 4 web-based databases: TargetScan, miRanda, RNAhybrid, and PicTar. Biological functions of target genes were predicted with the PANTHER Classification System. We identified 39 differentially expressed miRNAs between 2 cell lines: 22 were upregulated in SNUOT-Rb1 cells, and the other 17 were overexpressed in Y79 cells. More than half of top 10 mRNA targets of hsa-miR-10b, hsa-miR-29a, hsa-miR-29b, hsa-miR-29c, and hsa-let-7c in SNUOT-Rb1 cells and hsa-miR-34a, hsa-miR-34c-5p, hsa-miR-124, hsa-miR-135b, hsa-miR-142-5p, and hsa-let-7i in Y79 cells were related with biological processes, which could affect the growth patterns of cells: cell adhesion, cell cycle, cell death, and cell division. On the basis of the data from the target analysis of each miRNA, we found out several miRNAs, which were differentially expressed and had targets of possible impact on progression of RB. From these analyses, we suggest that some differential miRNAs could have roles in miRNA-targeted treatments on RB.