Ablation characteristics of ultrashort laser pulses were investigated for pulse durations in the range of 130 fs–10 ps. Tissue samples used in the study were dental hard tissue (dentin) and water. We observed differences in ablation crater morphology for craters generated with pulse durations in the 130 fs–1 ps and the 5 ps–10 ps range. For the water experiment, the surface ablation and subsequent propagation of stress waves were monitored using Mach–Zehnder interferometry. For 130 fs–1 ps, energy is deposited on the surface while for longer pulses the beam penetrates into the sample. Both studies indicate that a transition occurs between 1 and 5 ps. © 2001 Society of Photo-Optical Instrumentation Engineers.