In vivo wound healing response post nonablative fractional laser treatment is evaluated. Seven healthy subjects receive treatments with a Fraxel re:store™ laser system on the forearm with pulse energies ranging from . The treatment sites are imaged at increments up to using confocal microscope z-stacks using -depth spacing. At least five individual microscopic treatment zones are imaged per subject, time point, and treatment energy. Images are analyzed for tissue structure and morphology to classify each lesion as healed or not healed, depending on epidermal re-epithelialization at each time point and treatment energy. Probit analysis is used to statistically determine the and probabilities for a positive dose response (healed lesion) as a function of treatment energy. Confocal observations reveal epidermal keratinocyte migration patterns confirmed with histological analysis using hematoxylin and eosin (HE) and lactate dehydrogenase (LDH) staining at at 0, 7, 16, and post-treatment. Results indicate that more time is required to conclude re-epithelialization with larger lesion sizes (all less than ) corresponding to higher treatment energies. For the entire pulse energy range tested, epidermal re-epithelialization concludes between post-treatment for and for .