The article presents data on the composition and structure of cyanobacterial-algal cenoses of various habitats of the Karlamanskaya Cave. The study identified 46 species and intraspecific taxa of cyanobacteria and algae belonging to 5 divisions (Cyanobacteria – 17 species and intraspecific taxa, Bacillariophyta – 12 species and intraspecific taxa, Chlorophyta – 14 species, Charophyta – 1 species, Ochrophyta – 2 species), 7 classes, 16 order, 28 families and 36 genera. Leptolyngbya boryana (Gom.) Anagn. et Kom., Oscillatoria rupicola (Hansgirg) Hansgirg ex Forti, Luticola mutica (Kütz.) Mann, Mychonastes homosphaera (Skuja) Kalina et Punс., Chlorella vulgaris Beijerink present the dominant complex of cyanobacteria and algae in all studied habitats. Cyanobacteria dominate in all biotopes of the cave except aquatic ones where diatoms predominated. The maximum number of species was found in the soil at the cave entrance and in the soil of the illuminated cave zone: 31 and 29 species respectively. The lowest number was found in the soil and on the walls (16 and 11 species respectively). Ecological analysis of cyanobacterium and algae revealed 12 life forms: Сh9B9P5X5CF5hydr4amph2PF1NF1C1M1H1. Most of the life forms were found in the illuminated cave zone: in the soil (10 forms), on the wall (10 forms) and at the cave entrance (11 forms). The ecobiomorphs composition of the dark zone is the poorest (5 forms).