Aim. To present difficulties involved in IQ assessment that are of importance for expert psychiatrists when determining the degree of the subject's accountability in forensic psychiatric expertise.
Case report. A case is described of a 44-yearold patient submitted to forensic psychiatric observation and examinations on the outpatient basis on several occasions. Since the quantitative results of the examinations conducted so far were different, they resulted in various diagnoses with different legal consequences.
Comment. Psychological diagnosis is not identical with psychometric assessment. In the IQ assessment the subject's functioning level must be taken into account. In the paper an attempt was made to indicate significant factors that may affect the IQ assessment.