Abstract This paper presents an overview of the explosion and fire problem on offshore topside structures. The role of quantified risk assessment is briefly discussed. Gas explosion mechanisms are described and available methods of predicting explosion overpressures are outlined. Methods of idealisation of overpressure time history for use in structural response analysis are given such that the important characterisctics of both loading and response are obtained. Fires are described in the context of both jet and pool fires. Fire load predictive techniques are considered and methodologies for describing the response of structures to these fires are described. The paper concludes with an examination of integrated fire and explosion resistance design, addresses some of the conflicts which arise in integrated design and suggests methods for overcoming them. Keywords: Offshore topside structures, quantified risk assessment, explosion, jet fire, pool fire, predictive methods, integrated design.