Oxaliplatin (L-OHP) is one of the key drugs against advanced, recurrent colorectal cancer, and FOLFOX4 regimen combination of l-leucovorin (l-LV)and 5-fluorouracil (5-FU)with oxaliplatin is a standard therapy in colorectal cancer. We performed a retrospective study that researched adverse events and relative dose intensity(RDI)to evaluate safety and feasibility of FOLFOX4 regimen.We administered 188 patients a FOLFOX4 regimen. To evaluate RDI, this study research dose modification and delay treatment procedure was done for 1 to 13 cycles.RDI of oxaliplatin is 89.1% (1-4 cycles), 81.4% (4-7 cycles), 78.2% (7-10 cycles), 69.0% (10-13 cycles). The factors of RDI decrease were hematologic toxicity(leucopenia, neutropenia, thrombocytopenia), peripheral neuropathy and allergic reaction. Moreover, peripheral neuropathy and allergic reaction often require therapy to be discontinued (peripheral neuropathy: 15.2%, allergic reaction: 20.3%).Feasibility of FOLFOX4 regimen is related to incidents of hematologic toxicity, peripheral neuropathy and allergic reaction. We should pay sufficient attention to these adverse events of FOLFOX4.