The central purpose of this review is to present a critical survey of iron sulphide occurrence in oilfield systems from an “oilfield scale viewpoint”, locating the issue of sulphide management in this type of context. A wide ranging review of many inter-related aspects of the chemistry and “engineering” of iron sulphide formation are tackled, with the objective of giving the oilfield chemist an up to date view of the current science, technology and “issues” in this area. There are a number of open issues in the prediction and mitigation of iron sulphide in its several forms and these are discussed in the appropriate sections; e.g. the issue of “soluble iron” and how this should be incorporated into our field prediction models.