Recurrent pregnancy loss is a common clinical problem in reproduction, occurring in approximately 1% of reproductive-aged women. A definite cause is established in no more than 50% of couples, and several alleged causes of recurrent pregnancy loss are controversial. Moreover, in the field of recurrent pregnancy loss, inappropriate emphasis often is given to unproven hypotheses and poorly designed clinical studies. Seeking a solution, some patients and physicians explore less-well-accepted etiologies and empirical or alternative treatments. This bulletin will provide the practitioner with a rational, modern approach to the management of recurrent pregnancy loss. New and controversial etiologies will be presented so that the practitioner can discuss them with couples who have a history of recurrent pregnancy loss.