The present study aimed to investigate the acute response of gilthead seabream ( ) juveniles exposed to temperature, salinity and ammonia stress. Radioimmunoassay was used to evaluate cortisol levels, whereas insulin-like growth factors ( and ), myostatin ( ), heat-shock protein 70 ( ) and glucocorticoid receptor ( ) gene expression was assessed trough Real-Time PCR. The presence and localization of IGF-I and HSP70 were investigated by immunohistochemistry. In all the stress conditions, a significant increase in cortisol levels was observed reaching higher values in the thermic and chemical stress groups. Regarding fish growth markers, gene expression was significantly higher only in fish subjected to heat shock stress while, at 60 min, gene expression was significantly lower in all the stressed groups. Temperature and ammonia changes resulted in a higher gene expression. Molecular analyses on stress response evidenced a time dependent increase in gene expression, that was significantly higher at 60 min in fish exposed to heat shock and chemical stress. Furthermore, the same experimental groups were characterized by a significantly higher gene expression respect to the control one. Immunostaining for IGF-I and HSP70 antibodies was observed in skin, gills, liver, and digestive system of gilthead seabream juveniles.