Femtosecond laser ablation selectively dissects subcellular components of the C. elegans neuronal circuit with submicrometer precision for studying the neuronal origins of behavior. We describe the theoretical basis for the high precision of femtosecond laser ablation in the target bulk. Next, we present the experimental setup and a worm rotation technique to facilitate imaging and surgery. We describe the damage caused by different pulse energies on cell bodies and neuronal fibers. Finally, we discuss the regrowth of neuronal fibers after surgery and its impact on behavioral study.