OBJECTIVES: . To describe cost associated to the treatment of different stages of colorectal cancer at the Social Security Mexican Institute (IMSS) from the health care payer's perspective. METHODS: . A cost study was made. Resource use and cost data were obtained from hospital (second and tertiary levels) records of 115 treated patients from July 2008 to February 2009 using the following inclusion criteria: patients older than 16 years with colorectal cancer histological diagnosis who accepted to be included in the protocol through informed consent. Although, patients excluded were those who showed a second malignant neoplasm or incomplete information. We calculate mean,standard deviation (SD), median, 25 percentil and 75 percentil for each clinical stage and statistical differences were estimated through ANOVA tests, p value <0.05 was considered significant to show differences. RESULTS: . The median total cost per patient was US $3,263.52 (US $2,111.29 to US $4,881.14), the mean cost per chemotherapy was US $484.16 (SD: US $113.95), mean cost to radiotherapy was US $402.40 (SD: US $57.20). The mean cost per patient in each clinical stage to chemotherapy was I: US $247.21 (SD: US $247.21), II: US $482.48 (SD: US $208.96), III: US $393.75 (SD: US $192.35), IV: US $986.17 (SD: US $631.59) and the non classified: US $386.88 (SD: US $105.18) p 0.521. CONCLUSIONS: . The results show that in México, in more expensive the treatment to patients with colorectal cancer  in clinical stage IV, the cheapest treatment was to patients in clinical stage I, the treatment to clinical stage II patients are the second most expensive according our results, probably associated to longer hospital stay.