Alterations of trace element concentrations adversely affect biological processes and could promote carcinogenesis. Only a few studies have investigated the degree of changes in copper and zinc levels in colorectal cancer (CRC). The aim of the present study was to compare the serum copper (Cu) and zinc (Zn) concentrations in patients with CRC from Iran with those of healthy subjects. Cu and Zn concentrations in the serum of 119 cancer patients and 128 healthy individuals were measured by atomic absorption spectrometry. We found a significant decrease in the total mean serum Cu and Zn concentrations in CRC patients as compared with the control group (137.5 ± 122.38 vs. 160.68 ± 45.12 μg/dl and 81.04 ± 52.05 vs. 141.64 ± 51.75, respectively). However, the serum Cu/Zn ratio in the patient group was significantly higher than that measured in the control group (p = 0.00). There was no significant difference in the mean values of serum Cu and Zn concentrations between young (<60 years) and elderly (≥60 years) patients. However, the Cu/Zn ratio in <60-year cases was significantly higher than that in ≥60-year age group (p < 0.05). In addition, mean serum Cu level in normal weight patients was significantly higher than that in overweight/obese cases (132.31 ± 87.43 vs. 103.81 ± 53.72 μg/dl, respectively) (p < 0.05). There was no difference in mean serum Cu and Zn concentrations in patients stratified by the site, stage, or differentiation grade of tumors. Our findings suggest that imbalance in Cu and Zn trace element level is associated with CRC and might play an important role in cancer development among Iranian patients.