Objectives:
The aim of this study was to compare the zinc and copper concentration in the group of patients with bipolar disorder (BD) and major depressive disorder (MDD).

Methods:
110 patients with the diagnosis of BD and 114 with MDD were qualified to the study. To assess the levels of microelements, the flame atomic absorption spectrometry (FAAS) was used in the case of zinc and the electrothermal atomic absorption spectrometry (ETAAS) was used in the case of copper.

Results:
There were no differences between concentration of zinc and copper in remission and depressive phase between patients with BD and MDD. Additionally, there were also no statistically significant differences in comparisons including type I and II, early or late phase of BD and MDD.

Conclusions:
The lack of differences in zinc and copper concentrations between patients with bipolar disorder and major depressive disorder might indicate that those disorders have similar etiology.