Purpose: The aim of this in vitro study was to analyze the morphology, diameter, depth, and volume of the cavities prepared in deciduous teeth using laser. Materials and Methods: Fourteen exfoliated teeth were irradiated with Er:YAG laser set at 200 mJ and 300 mJ of energy per pulse and a frequency of 10 Hz, applied for 10 s. The morphology, diameter, and depth of the cavities were measured on scanning electron micrographs using a modified cephalometric program, and the volume was calculated taking all these parameters into account. Results: The cavities presented a round shape, and a pattern of flakes or scales was observed in the ablated region. There was no significant statistical difference in the diameter of the cavities when 200 mJ (1033.37 µm) or 300 mJ (1083.75 µm) were used. The depth was statistically greater when the energy was increased (153.69 µm and 296.67 µm at 200 and 300 mJ, respectively). The volume was also increased when 300 mJ was used. Conclusion: SEM observations showed that the cavities produced were round or slightly oval. The diameter was not affected by energy level, but the higher energy level increased the depth and volume of the cavities.