The biological activities; antimicrobial, antioxidant and anticancer, of the red algae Galaxaura rugosa and Liagora hawaiiana were determined. The total ethanol, lipoidal matters, chloroform, n-butanol, aqueous extracts and powder of both algae showed and bacterial and antifungal activities. However, the chloroform extract of Galaxaura rugosa showed antibacterial activity against Klebsiella pneumoniae (24 mm, 0.15 mg/ml) higher than gentamycin (23 mm, 0.49 mg/ml). Moreover, the total ethanol, lipoidal matter and chloroform extracts showed antifungal activity (21, 22 and 25 mm, 1.25, 0.312 and 0.156 mg/ml) similar to the antibiotic Ketoconazole activity (23, 24 and 27 mm, 1.25, 0.312 and 0.156 mg/ml) against Aspergillus fumigatus, A. niger and Candida trobicalis, respectively. A good antioxidant activity (80.96%, IC50 = 27.8 mg/ml) was provided by Galaxaura rugosa. The anticancer activity results revealed that the lipoidal matters of Galaxaura rugosa and Liagora hawaiiana possessed antitumor activity (IC50 = 15 +/- 1.7 and 21.2 +/- 1.6, respectively) against lung carcinoma (A-549) better than vinblastine sulfate (IC50 = 24.6 +/- 0.7). Although, the lipoidal matters of Galaxaura rugosa and Liagora hawaiiana antitumor activity against cervical carcinoma (HeLa) and intestinal carcinoma (CACO-2) (IC50 = 10.2 +/- 0.6 and 12.2 +/- 0.6, respectively) preferable than vinblastine sulfate (IC50 = 59.7 +/- 2.1 and 30.3 +/- 1.4, respectively). (C) 2017 The Authors. Production and hosting by Elsevier B.V. on behalf of King Saud University.