Use of spiculisporic acid and/or a salt thereof as antidandruff agent, and cosmetic treatment process employing same. The present invention relates to the cosmetic use, especially for hair, of spiculisporic acid and/or a salt thereof as anti dandruff agent. The invention also relates to a cosmetic treatment process intended for eliminating dandruff and/or for reducing the amount thereof, comprising the application, to the hair and/or the scalp, of spiculisporic acid and/or a salt thereof, or of a cosmetic composition comprising it/them.