We aimed to investigate the expression of cancer susceptibility candidate 11 (CASC11) in ovarian cancer (OC) tissues and its role in doxorubicin (Dox) resistance. A total of 98 patients were included as subjects. Reverse transcription-polymerase chain reaction was employed to determine the expressions of CASC11 in OC and para-OC tissues, and in OC cells (A2780, SKOV3, OVCAR3 and A547) and human normal ovarian epithelial cells (IOSE-80) from these patients. OC SKOV3/R cell line with Dox resistance was established and transfected with small interfering (si)-CASC11 to down-regulate CASC11 expression. Based on the constructed nude mouse model of orthotopic transplanted tumor, the growth curves were plotted, and the changes in tumor volume and apoptosis were observed by hematoxylin-eosin staining. OC tissues had a significantly higher mRNA expression of CASC11 than that of para-OC tissues (P < 0.05). A547, OVCAR3, A2780 and SKOV3 cells had significantly higher mRNA expressions of CASC11 than that of IOSE-80 cells (P < 0.05). The transplanted tumor was significantly smaller in volume in the si-CASC11 group than that in the si-normal control (NC) group from the 8th days after transplanted tumor inoculation (P < 0.05). The tumor growth inhibition rate significantly rose in the si-CASC11 group in comparison with that in the si-NC group (P < 0.05). CASC11 has high expression in OC tissues. Knockout of CASC11 weakens the proliferative, invasive and migratory potentials and enhances the apoptotic potential of Dox-resistant OC cells, thereby reversing their Dox resistance.