The total synthesis of (+/-)-arohynapene B, an anticoccidial agent isolated from the fermentation broth of a fungal strain, has been achieved. The tetrahydronaphthalene ring was constructed by the Diels-Alder reaction between dimethyl acetylenedicarboxylate and the 1-(beta-acetoxyvinyl)cyclohexene derivative, which was prepared from 3,5-dimethylcyclohexanone via the Ag+-catalyzed rearrangement of the propargylic acetate derivative. The introduction of the dienylcarboxylic acid side chain was accomplished by the Horner-Wadsworth-Emmons olefination repeatedly utilizing ethyl diethylphosphonoacetate. Finally, careful removal of the protecting groups led to (+/-)-arohynapene B.