Objectives:
The purpose of the following study was to verify the psychometric properties of the Polish version of the Inventory of Complicated Grief.

Methods:
278 people who experienced loss of a close relative or a friend participated in the research on adaptation of the tool. The following research methods were applied: ICG (Inventory of Complicated Grief), BDI (Beck Depression Inventory), STAI (State-Trait Anxiety Inventory), IES-R (Impact of Events Scale-Revised), AHS (Adult Hope Scale), LOT-R (Life Orientation Test-Revised), GSES (General Self-Efficacy Scale), MSTAT-2 (Multiple Stimulus Types Ambiguity Tolerance).

Results:
The statistical analyses conducted as part of the research prove the Polish version of the ICG to be a reliable and valid tool (Cronbach’s alpha = 0.941). Amoderate positive correlation was noted between the overall ICG score and depression (r = 0.50; p < 0.001), post-traumatic stress disorder (r = 0.67; p < 0.001) and trait anxiety (r = 0.59; p < 0.001). The general ICG results also display negative correlation between variables related to positive expectations of the future: optimism (r = –0.37; p < 0.001), hope for success (r =–0.19; p =0.001), general self-efficacy (r = – 0.27; p < 0.001), and ambiguity tolerance (r = – 0.27; p < 0.001). The conducted confirmatory factor analysis (CFA) revealed that the one-factor model of the Polish version of the Inventory of Complicated Grief can be considered wellfitted to the data (correlation of measurement errors was allowed).

Conclusions:
Preliminary studies on the adaptation of the Polish version of the ICG prove, therefore, that it is a valid and reliable tool. However, further research is needed to help better understand the structure of complicated grief symptoms.