This chapter Sampling Issues in Research, is essential for planning of the research. It deals with the various types of sampling. While, we have dealt with almost all types of probability sampling used for biomedical research, we have also touched in brief the methods used for nonprobability sampling techniques followed in public health research. Cluster sampling technique has also been covered. Since adequate sample size is a must for all research and because, calculation of sample size poses huge problem to the beginner, we have given few model sample sizes for certain specific types of studies, which could be taken up and implemented by researchers in their debut work, though it is desirable that they calculate their specific sample size.