In vitro propagation of avocado (Persea americanaMill AbstractGiven the importance and potential development of avocado (Persea americana Mill.) cultivation in Colombia and its problems for an efficient field cultivation, which includes the genetic variability of propagated material and adverse phytosanitary conditions, the aim of this study was to develop a method for in vitro clonal propagation for avocado cv. Hass. In vitro introduction of apical explants and nodal segments was carried out from grafted parent plants. Etiolation pretreatment effect on the number of shoots formed and in vitro phenolization was evaluated in grafted parent plants and in explants under in vitro conditions, subject to photoperiod (12/12 hours) and darkness. Darkness conditions reduced significantly plant phenolization, and these in turn formed new shoots, which were higher and were also formed in a shorter time. During multiplication stage, using a WPM culture medium an effective control of phenolization was obtained. During subculturing there was a decreasing in apical explant elongation, but there was a significant induction of new shoots from nodal segments. However, only some segments reached the required height to keep the multiplication rate throughout subcultures. Finally, 82% survival rate of vitroplants was obtained during hardening.