The aim of this in vitro study was to detect and quantify an established marker of inflammation, prostaglandin E2 (PGE2), in blood samples harvested from radicular pulp stumps after coronal pulp amputation. Harvesting was achieved by a paper strip 'dip-stick' method and the volume of each sample estimated before storage at -80 degrees C. A competitive, plate-based enzyme immunoassay technique (EIA) was developed for detection and quantification of the inflammatory mediator assumed to be present in blood samples. Since this technique had not previously been used to assess pulp blood, steps in the development of harvesting, storage, extraction and validation of this sensitive assay are described. Thirty-nine single-blood samples were assayed and yielded detectable amounts of PGE2 ranging from 1.0 to 2641 ng mL-1. The results of this investigation indicate that the inflammatory mediator, PGE2 can be detected and quantified in small blood samples from pulp stumps. Further development may derive quantitative tests for determining the condition of pulp tissue in primary molar pulp treatment.