Aim: The aim of the study was to describe the prevalence and picture of PTSD among eye witnesses of flood, who had neither received any psychiatric treatment previously, nor experienced any other concurrent stressful life events that might have been an independent cause of the PTSD onset. Material and methods: Flood victim were interviewed between the 60th and 63rd month after the flood by the same psychiatrist using the Composite International Diagnostic Interview (CIDI), section A (concerning demographic data) and section N (referring to PTSD). They were visited at home, by previous appointment over the phone. The course of PTSD was analysed in two groups (of 47 and 50 respondents) distinguished on the ground of flood-related material loss. Results: The presence of PTSD was more frequent among those who had sustained severe loss due to the natural disaster (N = 30) than among persons who had experienced no significant loss (N = 30), with the PTSD ratios of 23.7 % vs. 7.2 % respectively. An analysis of symptom severity on the three main axes indicated a significantly higher prevalence of such symptoms on each axis in the group of victims who had experienced a permanent loss. In a vast majority of cases PTSD symptoms persevered for over a year, irrespective of the amount of loss. Conclusions: The higher severity of symptoms in persons who had sustained a permanent loss evidences a relationship between PTSD and prolonged stressful situation due to permanent flood-related loss. The duration of symptoms similar in both compared groups indicates a stronger effect of the major stressor as well as a negative effect of absence of psychological support for the victims.