Although several studies have described an increase in urinary zinc output in cancer patients, little attention has been paid to the excretion of copper. In this study, we investigated urinary excretion of zinc and copper, and serum levels of alpha-1 acid glycoprotein, an acute phase protein, in 22 patients with colorectal cancer. Urinary excretion of copper and zinc were significantly increased compared to the reference group (77 +/- 72 vs. 32 +/- 14 mumol/mol creatinine, P < 0.05, and 1.50 +/- 0.62 vs. 0.70 +/- 0.41, P < 0.002, respectively). In addition, a negative correlation was observed between urinary copper and serum alpha-1 acid glycoprotein (rs = -0.5256, P < 0.02). In conclusion, urinary excretion of copper, as well as that of zinc, appears to be elevated in colorectal cancer. The finding of a negative correlation between urinary copper and alpha-1 acid glycoprotein supports the postulated role of the latter in regulating renal glomerular permselectivity.