Administrative inspections are indispensable: without them there is no practical way to determine whether there is compliance with the plethora of health, sanitary, safety, and building regulations that ensure that living and working conditions remain tolerable. The need for administrative agencies to have this power does not, however, immunize inspections from the requirements of the fourth amendment. Administrative inspections "are subject to the governing principle that a search of private property, in the absence of consent, is 'unreasonable' unless authorized by a valid search warrant. This article discusses the continuing vitality of the Colonnade-Bisiwell exception to the warrant requirement after Marshall v. Barlow's, Inc., explains the elements of the exception, and examines the classes of cases in which a warrantless administrative search of private property is valid under the fourth amendment.