This paper presents a historical overview of the assessments of the Atlantic stocks of blue marlin ( Makaira nigricans ), white marlin ( Tetrapturus albidus ) and sailfish ( Istiophorus platypterus ) that have been conducted by the International Commission for the Conservation of Atlantic Tunas between 1977 and 2000. Details are presented on the data sets used and the models applied, noting the strengths and weaknesses of the assessments. The major causes of uncertainty in the current perception of the status of the stocks are related to some of the data used and to their interpretation, especially historical trends in catch per unit effort. In particular, there are uncertainties about historical catch data, including discards, and about the degree to which longline fishing effort overlaps with billfish habitat. The paper concludes with an account of the efforts that should be made to reduce these uncertainties.