This study continues our investigations concerning the interaction of phenol, catechol, 2,4-dichlorophenol (2,4-DCP), 2,4,5-trichlorophenol (2,4,5-TCP) and 2,4-dimethylphenol (2,4-DMP) with human erythrocytes. We focus on the effects of these compounds on erythrocyte membrane fluidity, as well as on their impact on membrane proteins. The fluorimetric method and fluorescent probes (ANS, DPH and TMA-DPH) were used to estimate the fluidity of erythrocyte membranes. SDS-gel electrophoresis was carried out to separate the proteins of the cell membrane. Additionally, an analysis of disturbances in size and shape of the erythrocytes by the application of the methods of flow cytometry and microscopic examination was performed. It was observed that phenol derivatives like 2,4-DCP, 2,4,5-TCP, 2,4-DMP and catechol induced changes in membrane fluidity and perturbations in the content of a cell’s membrane proteins. Changes in the level of spectrin, band 3 protein and low molecular weight proteins were also noted. Using three fluorescent probes we observed different changes in membrane fluidity on its different layers, depending on the structure and the concentration of the compound used. The application of flow cytometry and microscopic technique also demonstrated disturbances in the size and shape of erythrocytes. We concluded that chlorophenols induced more severe changes in erythrocyte membrane properties and phenol expressed the lowest toxicity.