Purpose: The Mini-ICF-APP is a simple, practical tool measuring activity limitations and participation restrictions in mental disorders according to the principles and categories of the International Classification of Functioning, Disability and Health (ICF). The aim of the study was to determine the basic psychometric properties of the Polish language version of the Mini-ICF-APP. Method: A total of 58 patients in the early stages of recovery were included. Each of them was independently assessed by three clinicians with varied professional backgrounds (psychiatrists, psychologists and other therapists) using the Mini-ICF-APP and measures of psychopathology (Brief Psychiatric Rating Scale-BPRS) and level of psychosocial functioning (Global Assessment of Functioning Scale-GAF; Personal and Social Performance Scale-PSP). Feasibility, reliability (internal consistency and inter-rater agreement), and validity (content, criterion and construct) were analysed. Results: Feasibility was concluded on the basis of positive feedback from clinicians, diversity of distribution and good item performance. Internal consistency was high, both when analysed jointly and separately for particular groups of clinicians. Measures of inter-rater agreement reached high values for the scale and were significant for each item. Criterion validity was indicated by high correlations with the GAF and the PSP, and slightly weaker with the BPRS. The construct validity of the Mini-ICF-APP was inferred