Although the mechanical and positional stresses of pregnancy are the primary inciting factors contributing to lumbosacral pain accompanying gestation, in approximately 1:10,000 cases a herniated disk (HNP) can be identified as the proximal cause of pain, Six patients are described, all of whom without antecedent history of pain presented with acute, disabling, gestational lumbosacral, and sciatic radiculopathy, Their ages ranged from 29 to 36, their parity from 0 to 1, and their gestational age at onset of symptoms from 6 weeks to 32 weeks, Each by magnetic resonance imaging (MRI) was identified as having an HNP, 2 at the L4-5 level and 4 at the L5-S1 level, During pregnancy, an MRT. evaluation permits a detailed spinal examination without the ionizing effects of x-ray and its acknowledged biological risk to the developing fetus, This potential for an immediate and accurate diagnosis has significant implications for the management and subsequent planning of delivery. (C) 1995 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation