The research goal is to develop efficient designs under realistic assumptions with applications to designing clinical trials and biomedical studies. There are three parts: (1) to develop multiple-objective optimal designs in clinical trials and biomedical studies, (ii) to develop optimal designs for longitudinal studies, and (iii) to develop efficient designs for understanding patients' ranking preferences to different dimensions in quality of life assessment. Results from part (i) and (ii) will provide more efficient designs in evaluating treatment protocols over time. In addition, the designs developed here are more versatile since they capture the goals of the researcher more accurately. Results from part (iii) of the research will provide an efficient way of understanding patients responses' to various health outcome measures by reducing the questionnaire burden on the patients. In all cases, analytical and numerical designs will be developed using modern technique and graphical tools. In addition, computer algorithms for generating these designs will be supplied for general use. The designs developed here are all efficient and can accomplish many practical objectives in clinical trials with a minimum use of resources. This is important in such times when it is increasingly costly to run experiments and clinical trials.