OBJECTIVE: To determine the serum level of the secretory endometrial protein, placental protein 14 (PP14) and progesterone (P) in women with ectopic gestation. DESIGN: Blood samples were collected prospectively and preoperatively. Reference range was determined from a prospective population of 98 women with uncomplicated pregnancies and normal outcome. SETTING: The women were admitted to a university hospital. PATIENTS: Fifty-nine women with laparoscopically verified ectopic pregnancy entered the study. INTERVENTION: At the time of diagnosis PP14 and P were measured. MAIN OUTCOME MEASURE: After observing the low serum levels of PP14 and P, a correlation analysis was made and compared with the findings in normally pregnant women. RESULTS: A significant positive correlation was found between the level of PP14 and P (P less than 0.00002), not found in normal intrauterine pregnancies. CONCLUSIONS: These findings suggest that the regulation of the PP14 production involves either a control mechanism from the ovary or is mediated by paracrine secretion.