In search for bioactive products, three zoanthid species (Zoanthus spp., Palythoa tuberculosa and Palythoa mutuki) were collected from offshore zone of Hengam Island. Three extracts of each zoanthids (methanol, dichloromethane (DCM) and n-hexane) were tested for antifungal and antibacterial activities against certified strains of bacteria (two Gram-positive: Bacillus subtilis, Staphylococcus aureus and three Gram-negative: Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris) and fungi (Candida albicans, Microsporum gypseum, Microsporum canis) through the disk diffusion assay. Cytotoxic activity of these extracts was evaluated against Artemia nauplii. The results showed that 8 extracts (88.88%) of the zoanthids were active against at least one bacterial strain and 6 extracts (66.6%) were active against at least one fungus (the activity against bacteria was moderate). Also, minimum inhibitory concentrations (MICs) of the extracts with desirable (inhibition zone more than 9mm) in the previous stage were assessed. Among the 9 zoanthids extract, 88.88% showed activity against some of the five bacteria, and 66.6% showed activity against some of the three fungi. The most active zoanthid extract against three fungi was dichloromethane extract of the Zoanthus ssp. that showed promising antifungal activity against Candida albicans in vitro models. The minimum inhibitory concentrations and LC₅₀ values of dichloromethane extract of Zoanthus ssp were 125μg/mL and 181μg/mL, respectively. Therefore, this extract can be a candidate for candidiasis therapy.  LC₅₀ of DCM, crude extract of Palythoa mutuki was 31µg/ml, showing high toxicity. This is the first report of biological activities of marine zoanthids from an Iranian Island of Persian Gulf.