To determine the diagnostic value of serum levels of copper, zinc and the Cu/Zn ratio in patients with hematological malignancies compared to gender- and age-matched control subjects. A total of 44 patients with recently diagnosed and non-treated hematological malignancies were included: 17 lymphoma (11 non-Hodgkin), 15 acute leukemia (10 myeloblastic), and 12 with chronic leukemia (8 granulocytic); 95 healthy subjects were included. Copper and zinc serum levels were measured with a Perkin Elmer (model 2380) atomic absorption spectrophotometer. Serum copper levels (microgram/dL) were significantly lower in healthy subjects (54.4 +/- 8.9, p < 0.05) compared to patients with lymphoma (93.7 +/- 37.5), acute leukemia (80.6 +/- 44.6) or chronic leukemia (95.7 +/- 28.9) while serum zinc levels (microgram/dL) were significantly higher in healthy control subjects (100.4 +/- 14, p < 0.05) compared to patients with lymphoma (77.2 +/- 22.6), acute leukemia (66 +/- 15.6), or chronic leukemia (74.8 +/- 14.7). The Cu/Zn ratio was significantly lower in healthy subjects (0.54 +/- 0.13, p < 0.05) than in patients with lymphoma (1.21 +/- 0.5), acute leukemia (1.22 +/- 0.7), or chronic leukemia (1.28 +/- 0.4). Twenty three patients died during a mean follow-up period of 13 months and their serum zinc levels were significantly lower (68 +/- 21) than in the living patients (76 +/- 15, p < 0.05). Cu/Zn ratio is significantly higher in patients with lymphoma or acute and chronic leukemias compared to gender- and age-matched control subjects.