Aim: to investigate the antifungal effect of spirulina plantensis against candida albicans. Materials and methods: In the present study, we used 60 adult rats weighing between 150 and 200gm. The rats were divided into three equal groups: Group I: Animals served as controls, Group II: Animals were subjected to Candida albicans inoculation on the dorsal surface of the tongue and received systemic antibiotic treatment, Group III: Animals were subjected to Candida albicans inoculation on the dorsal surface of the tongue under systemic antibiotic treatment and then received 15 mg/kg body weight Spirulina platensis extract orally by gastric gavage daily. After 3 weeks, by cervical dislocation, animals of the three different groups were sacrificed. Tongue specimen were dissected from each rat and prepared for histological staining done with Haematoxylin & Eosin and transmission electron microscopic examination. Results: histological examination revealed atrophy of the lingual epithelium and the surface layers was infiltrated with candida yeasts in-group II while in Group III the papillae begin to regain their normal appearance with decreased infiltration of candida to the superficial layers. Ultrastucturely, showed normal appearance of different layers of the lingual epithelium in-group I. Group II: Candida albicans yeasts invaded the keratin layer. The different layers of the lingual epithelium appeared with severely widened intercellular spaces and destructed desmosomal junctions. Group III: keratin layer appeared with disappearance of candida spherical plastopores. The different layers of the lingual epithelium showed less widened intercellular spaces and less destructed desmosomal junctions. Conclusion: Spirulina plantensis can be useful against candida albicans instead of the traditional antifungal drug.