Amphiphilic enediyne-cored dendrimers were prepared as pure cis and trans isomers. All dendrimers were flourescent to give fluorescence quantum yield of 0.10-0.64, and they underwent efficient photochemical isomerization with quantum yields of 0.22-0.50 in THF. In water, other photochemical reactions took place. Fluorescence or triplet lifetimes were also strongly affected by dendrimer generation and solvent polarity. The structure-photochemical property relationship of new photoresponsive dendrimers is discussed.