Traditional Chinese medicine (TCM) is now used by a broad cross-section of the western community. It offers some attraction because it provides new options for treatment, an individualized approach, and potentially avoidance of harsh drugs or surgery. However, despite this growing popularity there is debate as to its evidence base. Few TCM trials have been performed in the West, and previous Chinese TCM trials have been perceived to lack methodological rigour. Establishing and applying stronger clinical trial methodologies in TCM is imperative for its integration with modern medicine and achieving the end goal of creating options for patient care. A clinical trial was designed using a variety of approaches to promote methodological rigour whilst allowing the flexibility required in TCM practice. Irritable bowel syndrome (IBS) was selected as the disease focus, creating the possibility of tailoring TCM treatments to the variable clinical presentations of IBS. Patients were randomised to receive individually tailored treatment (n = 38), a standard Chinese herbal formulation (n = 43), or placebo (n = 35) for 16 weeks. Patients, gastroenterologists and herbalists were all blinded as to treatment group. Both standard and individualized treatments were significantly more effective than the placebo treatment on all key outcome measures. However, this study failed to confirm the added value of tailoring treatments. Chinese herbal formulations individually tailored to the patient proved no more effective than the standard treatment on all measures. Nevertheless, the trial demonstrates it is possible to test individualization of treatment whilst adhering to conventional trial protocols. Clinical trials can be designed that accommodate nuances of TCM practice. This study also shows Chinese herbal medicine may offer assistance to some patients with IBS and may prove as effective as current pharmaceutical approaches. Further validation of TCM interventions is required.