Lumbriculus variegatus is a segmented oligochaete annelid worm. Under laboratory conditions, its main form of reproduction is asexual fragmentation with rapid regeneration of the missing body parts. Damaged worms also rapidly and completely regenerate missing body parts. Research in planaria shows that gap junction function is important for proper anterior/posterior patterning during regeneration (Nogi & Levine, Develop Biol 287: 314-335, 2005; Oviedo et al., Develop Biol 339: 188-199, 2010). Blockage of gap junction function causes the growth of an ectopic head during regeneration. We hypothesized that the gap junction blocker 2-octanol could induce formation of an ectopic head in regenerating worm fragments. Worms were cut into three equal segments and then exposed to octanol concentrations ranging from 0.0025% to 0.01% or control pond water (n = 10 worms/concentration). Regenerating regions of the fragments were photographed and measured for growth using ImageJ. Octanol exposure reduced the amount of regeneration from all of the cut surfaces. In most cases, regeneration of octanol-treated worms produced normal head or tail morphology, although reduced in size. However, one worm treated with 0.01% octanol produced an ectopic head from the posterior surface of a middle fragment, and two worms at this concentration produced posterior tumorous masses. We will continue to experiment with amputation and treatment protocols in an attempt to increase the percentage of ectopic heads produced. Electrophysiological methods will be used to determine if an ectopic head remodels the sensory fields of the medial and lateral giant nerve fibers.