In recent years novel potential pharmocological candidates have been looked for in animal, seaweed, sponge, fungi and marine bacteria resources. In this study, matrix metalloproteinases (MMPs) that play an important role in metastasis, arthritis, chronic inflammation and wrinkle formation were used as target enzymes to screen therapeutic agents. The inhibitory effects of several marine algae including green algae (5 species), red algae (18 species) and brown algae (4 species) methanolic extracts on MMPs were investigated in human dermal fibroblasts and human fibrosarcoma cell line (HT1080 cells) using gelatin zymography. In human dermal fibroblasts, the inhibition of MMP-2 was observed in Laurencia okamurae, Polysiphonia japonica, Grateloupia lanceolate and Sinkoraena lancifolia of red algae. In contrast, MMP-2 activation was enhanced in Enteromorpha compressa and E. linza of green algae, and Peltaronia bighamiae and Sargassum thunbergii of brown algae. In human fibrosarcoma cells, MMP-9 activation was decreased in the presence of S. thunbergii of brown algae, Polysiphonia japonica in red algae and E. compressa and E. linza of green algae. The interesting finding is that E. compressa and E. linza of green algae, and S. thunbergii of brown algae exhibited a positive effect on MMP-2 in normal cells, but a negative effect on MMP-9 in cancer cell lines. These results suggest that E. compressa and E. linza of green algae, and S. thunbergii of brown algae contain potential therapeutic ingredients for cancer treatment.