Introduction: Clinical trials are essential in the advancement of global scientific knowledge. The role of nurses at SQCCCRC-UMC has become more significant because of their direct role in caring for clinical trial participants. This necessitated building their capacity through training to care for trial participants as per the International Council of Harmonization- Good Clinical Practice (ICH- GCP). Objectives: This study aims to investigate the effect of a capacity-building initiative that includes conducting Clinical Trial Workshops (CTW) and getting nurses certified in online ICH-GCP. Method: 21 CTW were conducted. Pretest and posttest scores to check knowledge were collected from 2022 to 2024 and analyzed using paired t-tests to compare averages. Nurses were also asked to submit ICH-GCP certification to the clinical trials department (CTD) for record keeping. Results: CTW had a total of 171 participants composing of 96% of nurses (n=165). Those nurses accounted for 50.6% of the total nursing workforce (n=326). 88.5% (n=146) of those nurses completed both the pretest and posttest. The mean posttest score (87.2%) was compared with the mean pretest score (68.5%) showing an average increase of 19 %, which indicated statistical significance. (CI=95%, t=0.05). 86 nurses have completed ICH-GCP certification during the same period. (26.4 % of all nurses, n=326). Conclusion: The capacity building approach significantly improved nurses’ knowledge about clinical trials which can potentially aid in caring for patients in clinical trials. Additional research is needed to assess the long-term impact of this approach on nurses’ attitude in caring for those patients.