Microalgae are sunlight-driven cell factories that are able to efficiently utilize CO2 for the production of biochemicals: polysaccharides (alginates, carrageenans, agars), proteins, vitamins, carotenoids, polyunsaturated fatty acids, sterols and others. Some algal taxons and their biotechnological products application in pharmaceutical, cosmetic and food industries: Aphanizomenon flos-aquae produces mycosporine-like amino acids used as UV-screening agent; Amphidinium sp. – macrolides amphidinolide as antitumoral remedy; Ascophyllum nodosum – proteins used in cosmetics as anti-aging agent; Chlorella sp. – proteins, carotenoids, triglycerides and hydrocarbons as immune stimulator and free radicals scavenger; Ch. zofingiensis – astaxanthin as antioxidant; Ch.vulgaris – biochemicals stimulating collagen production in the skin; species from division Dinoflagellata – okadaic acid, gonyautoxins used as experimental tools for investigations on neurodegenerative diseases; Dunaliella salina – B-carotene used as colorant, antioxidant, and cancer-preventive properties; Nostoc flagelliforme – pigments echinenone and myxoxanthophyll, allophycocyanin, phycocyanin and chlorophyll, 19 amino acids, vitamin B12, cryptophycin used for the treatment of diarrhea and hepatitis; Haematococcus pluvialis – astaxanthin as antioxidant, used in nutraceutical, cosmetic, food and feed industries; Spirulina sp. – proteins, glinolenic acid, vitamins, phycocyanin, phenolics, applicated as anti-aging agent, nutritional supplements, and infant formulas. Microalgal components are used in cosmetics as an antioxidant and water-binding agents. Many blue-green algae are capable of producing toxins used as pharmaceuticals. Microalgae are the major source of bioactive compounds which possess antiviral, anticancer, anti-HIV, several neurological and cardiovascular activities, also can improve immunity and fertility. There is indeed a wide range of applications of microalgae in biotechnology and a great potential to further exploit the rich microalgae resources for various biotechnological applications in medicine. They are potential sources of high-value products that may lead to the discovery of new generation of drugs and valuable food additives for physiological and balanced food.