"Bunk science" is a term used to describe what appears to be genuinine scientific research, but is in fact not valid. "Bunk scientists" are accused of attempting to establish opinions or unverified claims as fact through sophistic reasoning or by using (often purposely) badly-designed experiments.

The term may imply that the "bunk scientist" is working to support some kind of agenda, such as a religious belief, or to further the business interests of a sponsoring company. In other cases it implies that an entire apparently scientific field, usually a social science like psychology or sociology, is in fact devoid of scientific validity.

See also pseudoscience, junk science.