In the field of pharmacology, a selective receptor modulator or SRM is a type of drug that has different effects in different tissues. An SRM may behave as an agonist in some tissues while as an antagonist in others. Hence selective receptor modulators are sometimes referred to as tissue selective drugs or mixed agonists / antagonists. This tissue selective behavior is in contrast to many other drugs that behave either as agonists or antagonists regardless of the tissue in question.

Classes of selective receptor modulators include: