The purpose of the present study was to identity ways to prevent negative side effects in homechemotherapy. We conducted continuous hepatic arterial infusion chemotherapy (CHAI) in 122 cases of unresectable hepatic metastases from colorectal cancer. We continuously administered 5-FU at 250 mg/day for 7 days using a pump system. We also conducted systemic chemotherapy (FP therapy) in 145 cases of advanced or recurrent colorectal cancer in our outpatient clinic. Based on these experiences, we analyzed the problems of homeochemotherapy. The rate of negative side effects was 15.1% with CHAI. More than half were cases of abdominal pain. Because we had established an observation system for emergency cases, there were no fatal accidents. With FP therapy, about 40% of patients had gastrointestinal discomfort, but the rate of those with higher than grade 3 was low (1-2%). We conclude that it is very important to establish a hospital system to respond quickly to any negative effects of homeochemotherapy.