Scientists have been able to discover new compounds that can be used for the treatment of diseases; antimicrobial, anti-tumoral, such as areas of continuous research in detail. The uses of antimicrobial substances obtained from plants; The use of processed or raw materials, alternative medicine, natural therapies, pharmaceutical raw materials, is widely distributed as an alternative to pesticides in agriculture. It is known that most of the mosses (Bryofit) show antimicrobial effect against bacteria and fungi. Almost all varieties of bryofit; insect larvae, fungi, snails, mammals and bacteria are not damaged. The reason for this is that oligosaccharides, sugar alcohols, fatty acids, amino acids, aliphatic compounds, biological compounds, phenolic and aromatic compounds in bryophytes provide protection against these organisms. Turkey in terms of bryophytes with rich vegetation and the location has a lot of variety and is easy to obtain. In addition, it has been determined that many different species have anti-carcinogenic effects. The aim of this study was to investigate the cytotoxic effect of Platyhypnidium riparioides, Hypnum andoi, Syntrichia ruraliformis moss species on HCT116 (human colorectal cancer cells). Extracts were prepared from 3 different species of moss using Soxhlet extraction method. The extracts were applied to colon cancer cells at various concentrations for 24, 72 hours and 7 days and 50% of the maximum inhibitory concentration (IC50) values were determined. Cytotoxic activity was determined from 3- (4,5-Dimethylthiazol-2-yl) -2,5- diphenyltetrazolium bromide (MTT). Changes in cell morphology were examined with inverted microscope. As a result, Platyhypnidium riparioides, Hypnum andoi, Syntrichia ruraliformis species significantly reduced colorectal cancer cells at 72 hours. It was determined that colonized cell groups disappeared from place to place and spherical type cells increased. Accordingly, we can say that these species have cytotoxic effects. However, further investigation is needed to understand the mechanism that causes this.