Used in the diagnosis or treatment of diseases; prepared naturally from sources such as plants, microorganisms, minerals and animals or drugs prepared semi-synthetic or synthetically can cause cytotoxicity by affecting cells. Whether a pharmaceutical that is likely to be a drug or any pharmacological agent whose toxic effect is unknown has a toxic effect on the cell is determined by in vitro cytotoxicity tests in cell cultures before testing it in vivo on living mammalian subjects. For this, it is started from the dose of the minimum concentration at which the drug, whose toxicity will be investigated, will be effective. Subsequently, drugs prepared at different concentrations are applied to cell cultures. Considering the half-life of the pharmacological agent to be applied to cell cultures, any of the cytotoxicity tests with different mechanisms and sensitivities are applied at certain time intervals. In this research, on the one hand, it was aimed to explain how the cytotoxicity of pharmacological agents applied to cell cultures in vitro was tested and interpreted, on the other hand, many different pharmacomolecular analyzes such as colorimetric, fluorometric and luminometric were included.