Insulin resistance is one of the major aggravating factors for metabolic diseases. There are many methods available for estimation of insulin resistance which range from complex techniques down to simple indices. For all methods of assessing insulin resistance it is essential that their validity and reliability is established before using them as investigations. The reference techniques of hyperinsulinemic euglycemic clamp and its alternative the frequently sample intravenous glucose tolerance test are the most reliable methods available for estimating insulin resistance. However, many simple methods, from which indices can be derived, have been assessed and validated e.g. homeostasis model assessment (HMOA), quantitative insulin sensitivity check index (QUICKI). Given the increasing number of simple indices of insulin resistance it may be difficult for clinicians and researchers to select the most appropriate index for their studies. In planning studies on insulin resistance and selecting a suitable index, a number of important factors need to be considered by investigators, the principle one being the nature of the study to be undertaken. Where possible the hyperinsulinemic euglycemic clamp, as the most accurate technique available, remains the first choice but simpler and inexpensive methods may be appropriate provided the investigator is aware of their limitations.