BACKGROUND: It is getting more difficult to involve appropriate investigators in clinical trials. Knowing what investigators want from sponsor initiated clinical trials would help industry cooperate with investigators more efficiently. This study aims to describe the incentives for investigators choosing to participate or not and perform well in sponsored clinical trials. METHODS: Investigators who have participated in GSK sponsored clinical trials were interviewed face-to-face or through e-mail using the standardized questionnaire. Investigators were asked to choose five items and determine the ranking or those five items. RESULTS: Questionnaires answered by 122 investigators were collected. The top three incentives were "Academic merit" (108, 88.5 %), "Expectation of treatment potentially helpful to patient" (101, 82.8 %), and "Access to new treatments" (92, 75.4 %). The disincentives and the factors affecting an investigator's performance were analyzed separately because of the different questionnaire between investigators for medicine and vaccine. Investigators for medicine choose as disincentives "Insufficient time" (43, 61.4 %), "Difficult protocol" (41, 58.6 %), and "Adverse event concerns" (41, 58.6 %). Vaccine investigators pointed out "Limited support staff" (41, 78.8 %), "Insufficient time" (40, 76.9 %), and "Difficult blood sampling" (333, 63.5 %) as disincentives. Factors adversely affecting an investigator's performance showed similar results to those of disincentives. CONCLUSION: Investigators focused on academic curiosity and patients and insufficient time mostly inhibits them from participating and performing clinical trials. Our results would help industry cooperate with investigators more efficiently, finally making companies perform clinical trials more effectively.