This article presents the sequences followed in order to maximize the yield of laboratory assistive diagnosis of parasitic infections in the physiologic passage and/or collection of specimens for those parasites producing pathologic disease in the gastrointestinal tract and liver. The advantages and disadvantages of the many methods available to the clinician and laboratorian in the examination of those specimens are presented in a work-flow mode. The controversy relative to the current practice of controlling unwarranted specimen submission and the reasons for their rejection of limited examination and interpretation are discussed. Quality assurance and safety practices are also addressed.