We used a P[GAL4] enhancer-trap line, C161, in conjunction with the UAS-lacZ reporter construct to visualize the central projections of a defined set of thoracic and abdominal sensory neurons in a disconnected (disco) mutant background. The results show defects in the organization of sensory axons in the larval and adult central nervous system. The defects are indicative of problems with axon growth and development and include (a) poor axon fasciculation, (b) aberrant axon growth, (c) excessive terminal branching, and (d) ectopic innervation. Sensory neuron identity appears to be normal. The defects are comparable to those previously described for larval photoreceptor and adult retinular cells in disco mutants and extend the known effects of this mutation. Reduced larval and adult viability are likely to result from locomotory defects related to the disruption of the sensory system.