A historical analysis with statistical investigation on accidental events in the oil industry from the beginning of the XX century till now, was performed in order to identify historical trend and go deeper into accident causes. The classification methodology was developed referring to three headings, namely plant/process, environment and organization and trying to go deeper into the analysis of the causes of the accidents reported and understand more of what is probably behind the accidents. The accident types and severity were studied, plotting the accumulated frequency-fatality curve for each item. In the subsequent applicative phase, we applied a similar classification approach to near-misses directly collected over nine years observation in a large downstream oil firm. The historical analysis was extended on each section of the refinery, paying a careful attention to all causes and consequences of the event. Data were structured for analyzing trends and identifying possible precursors of unwanted events. According to the step-by-step approach we try to evidence how immediate causes of a near-miss could be linked in some kind of causal chain to underlying causes that should be controlled by middle or higher management, or are part of the corporate safety culture. (C) 2012 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.