We describe the evaluation of doxorubicin-loaded PEG-PE micelles targeting using an ovarian cancer cell spheroid model. Most ovarian cancer patients present at an advanced clinical stage and develop resistance to standard of care platinum/taxane therapy. Doxorubicin is also approved for ovarian cancer but had limited benefits in refractory patients. In this study, we used drug-resistant spheroid cultures of ovarian carcinoma to evaluate the uptake and cytotoxicity of an antibody-targeted doxorubicin formulation. Doxorubicin was encapsulated in polyethylene glycol-phosphatidyl ethanolamine (PEG-PE) conjugated micelles. The doxorubicin-loaded PEG-PE micelles (MDOX) were further decorated with a cancer cell-specific monoclonal 2C5 antibody to obtain doxorubicin-loaded immunomicelles (2C5-MDOX). Targeting and resulting toxicity of doxorubicin-loaded PEG-PE micelles were evaluated in three dimensional cancer cell spheroids. Superior accumulation of 2C5-MDOX compared to free doxorubicin or untargeted MDOX in spheroids was evidenced both by flow cytom-etry, fluorescence and confocal microscopy. Interestingly, even higher toxicity was measured by lactate dehydro-genase release and terminal deoxynucleotidyl transferase dUTP nick end labeling of targeted doxorubicin micelles in Bcl-2 overexpressing adriamycin-resistant spheroids. Overall, these results support use of spheroids to evaluate tumor targeted drug delivery.