Artificial intelligence is rapidly reshaping clinical research, offering both transformative opportunities and important cautions. This article explores how generative AI is already improving core elements of clinical trials, including patient recruitment, eligibility screening, trial design, simulation, and the use of digital twins. Emerging evidence suggests AI can reduce screening time, enhance equity, and improve trial efficiency, while early applications in drug discovery hint at faster and more productive development pipelines. However, these advances are tempered by significant limitations. Ethical concerns surrounding data privacy, intellectual property, transparency, and bias remain unresolved, and successful computational predictions do not always translate into real-world clinical benefit. Overall, the article provides a balanced, evidence-informed view of where AI is delivering value today—and where careful oversight, validation, and governance are still essential as the technology continues to evolve.