Recurrent miscarriage is a relatively frequent but poorly understood disorder because of clinical heterogeneity arising from the lack of standardization of definitions and diagnostic evaluation. The diagnostic approach varies from clinic to clinic and, in a significant proportion of couples, no cause can be identified. In others, multiple causes are present. Thus, the approach of offering treatment for the first abnormal test may not be prudent. Ideally, a comprehensive approach to evaluation is required to identify factor(s) associated with recurrent miscarriage. The current approach should be to identify chromosomal abnormalities, uterine anomalies, cervical incompetence, endocrine dysfunction, thrombophilias, and alloimmune abnormality. Agreement among investigators on the definitions and evaluation process will improve the understanding of this disorder so that more valid and useful studies on treatment efficacy can be undertaken to improve the outcome for couples with recurrent miscarriage. (C) 2004 Published by Elsevier B.V.