This study presents the first detailed morphometric measurements of wild caught black-and-white ruffed lemurs (Varecia variegata) from the eastern rainforests of Madagascar and aims to quantify the morphological variation present throughout their recognized range. One hundred and forty-four adult and juvenile individuals from 15 sites were sampled for 20 cranial, dental and postcranial morphometric and body mass measurements. Data were collected from an equal number of male and female individuals sampled across seasons over a 7-year period (1999-2002, 2004-2006). Results indicate that adult body mass and morphometric measurements varied between sexes across sites; however, the only significant intersexual difference found was that females possessed, on average, longer tails than males. Contrary to previous studies, significant seasonal variation could not be detected in either male or female body mass or testicular volume (i.e., breeding vs. nonbreeding, food-scarce vs. food-abundant seasons). Measurements did, however, vary significantly by site and subspecies, though clinal variation could not explain these differences. The introduced population from Nosy Mangabe exhibited significantly lower body mass and overall body length than all other populations; however, this distinction may not have been attributable to natural variation, and may have instead resulted from the ecologically restrictive habitat (e.g., unusually high lemur population densities, limited food resources, ecological isolation) of this introduced population. Finally, although fore-to-hindlimb, brachium-to-thigh and hindlimb indices were comparable to previous values, forelimb indices calculated here deviate significantly from previous reports, placing V. variegata within the upper range of lemurid taxa. It is currently unknown whether this is an artifact of sampling methods (i.e., live vs. skeletal specimens) or whether this is an avenue that warrants further investigation.