Intraperitoneal (IP) chemotherapy is a promising post-surgical therapy of ovarian cancer, but the full potential is yet to be realized. To facilitate IP chemotherapy of ovarian cancer, we developed an in-situ crosslinkable hydrogel depot containing paclitaxel (PTX) nanocrystals (PNC). PNC suppressed SKOV3 cell proliferation more efficiently than microparticulate PTX precipitates (PPT), and the gel containing PNC (PNC-gel) showed a lower maximum tolerated dose than PPT-containing gel (PPT-gel) in mice, indicating greater dissolution and cellular uptake of PNC than PPT. A single IP administration of PNC-gel extended the survival of tumor-bearing mice significantly better than Taxol, but PPT-gel did not. These results support the advantage of PNC over PPT and demonstrate the promise of a gel depot as an IP drug delivery system.