The present study aimed to examine the expression and activation of MAPKs (p38 MAPK, ERK1/2, and JNKs) in red blood cells (RBCs) of the gilthead sea bream, Sparus aurata, during thermal stress and investigate their involvement in the expression of heat shock proteins. The data showed that only p38 MAPK is detected in RBCs of Sparus aurata and it is phosphorylated and activated during exposure to increased temperature. Induction of Hsp70 in thermally stressed RBCs was abolished in the presence of the p38 MAPK inhibitor, SB203580, suggesting the involvement of the kinase in this response. This mechanism might play a cytoprotective role in the RBCs of the gilthead sea bream. © 2012 WILEY PERIODICALS, INC.