The "Rule of Five" is widely accepted in drug discovery to predict oral bioavailability of drug candidates. Accordingly, the "Rule of Three" has been proposed in order to specify the ideal molecular properties of fragments. The purpose of this rule is to optimize both compound synthesis and drug discovery processes. The guidelines of the "Rule of Three" indicate that fragment molecular weight should be less than 300, and the c LogP value, which is a measure of lipophilicity, should be less than or equal to 3. Moreover, the number of hydrogen bond donors and acceptors for fragments should be three or less, respectively. Overall, abiding by these criteria provides a good starting point in designing compounds for pharmaceutical use.Does the molecule adhere to the rule of three?