The smooth hammerhead shark Sphyrna zygaena (Sphyrnidae) is regularlycaught as bycatch in pelagic longline fisheries, but is one of the least studied of allpelagic sharks. Recently, ICCAT (International Commission for the Conservation of AtlanticTunas) issued recommendations underlining the need for more studies on the life historyparameters of this and other pelagic shark species. To this end, the age and growth ofS. zygaena were studied in the Eastern Equatorial Atlantic Ocean, in anarea where growth parameters were not yet available for this species. Data from 139specimens, caught between June and September 2009, ranging in size from 136 to 233 cm forklength (FL), were analysed. Preliminary trials were carried out to assess the mostefficient growth band enhancement technique. These indicated that sectioning the vertebraeinto 500 μm sections followed by staining with crystal violet producedthe best results. Growth models were fitted using the traditional von Bertalanffy growthequation and a modification of this equation using a known size at birth. Growth modelswere compared using the Akaike information criterion (AIC). The von Bertalanffy growthequation seemed to be the most adequate model to describe growth in this species, withresulting growth parameters of Linf = 272 cmFL, k = 0.06 year for males andLinf = 285 cm FL,k = 0.07 year for females. In the first four years of life, S.zygaena grows 25 cm per year on average, but its growth slows down in laterlife. Future stock assessment models should incorporate these age and growth parametersfor species management and conservation.