A method for maintaining consistent unit relationships during graphical pharmacological computational model construction is disclosed. A graphical user interface is presented through which a user may place and connect objects representing pharmacokinetic and pharmacodynamic elements. The user may specify units definitions for variables and constants using unit expressions. As the objects are converted into an internal format representing the statements of the corresponding computational model, the unit expressions are included in this internal format as multidimensional data type information. This multidimensional data type information is regularly and automatically propagated for each statement in the internal format to identify inconsistent units. When such inconsistent units are identified, a warning message is generated to notify the user, substantially immediately after the inconsistent units are created.