Inflammation mediated by the innate immune system is the organism's protective mechanism against infectious environmental risk factors. Uncontrolled acute inflammation can become chronic, contributing to various chronic inflammatory diseases such as arthritis, asthma, autoimmune diseases, and atherosclerosis. Although microalgae are increasingly receiving attention as a source of bioactive molecules with therapeutic potential for various human diseases, the underlying mechanisms are not yet well understood. In the present study, we investigated the molecular mechanisms underlying the anti-inflammatory and anti-aging activities of ethanol extracts of Antarctic freshwater microalga Micractinium simplicissimum. Using RAW 264.7 macrophages, microalgal extracts exerted anti-inflammatory activity by regulating the major inflammatory indicators including cyclooxy-genase (COX)-2, interleukin (IL)-6, inducible nitric oxide synthase (iNOS), tumor necrosis factor (TNF)-α and nitric oxide (NO). Besides, we observed the anti-aging activity of the microalgal extract by suppressing MMP-1 production in human dermal fibroblast. Taken together, these data suggest that anti-inflammatory and anti-aging activities of Antarctic freshwater microalga, Micractinium simplicissimum, can provide new clues to understanding the molecular link between inflammation and diseases, and be a potential anti-inflammatory agent.