The history and advances in avocado breeding using morphological, molecular and mutation approaches is updated and the advances in morphological, molecular aspects and mutation-based breeding of avocado cultivars in Cuba for the development of lines with improved tolerance/resistance to abiotic and biotic stresses are summarized. An analysis of the genetic diversity among a set of 23 avocado cultivars was undertaken based on agronomical, morphological and DNA markers (amplified fragment length polymorphisms – AFLP and simple sequence repeats – SSR). A detailed illustrated catalogue considering 101 descriptors of the 19 most important accessions and a practical handbook to manage this crop under our conditions were published. While phenotypic variation reasonably reflected genetic distances, AFLP and SSR markers provided a more precise estimate of genetic distances among cultivars. These morphological traits and molecular markers, adding inverse sequence-tagged repeats and isozyme analysis, were compared in terms of their discriminating and informational power using the 17 most promising genotypes assembled from the Cuban avocado germplasm. Results showed that Discriminant Power (D) can be adopted successfully for discriminating capacity with morphological traits; morphological traits are less effective for cultivar identification in comparison with all molecular markers analyzed; a high degree of heterozygosity is detectable in avocado using SSR markers; and marker index (MI); and assay efficiency index values (Ai) are probable indicators of the discriminating capacity in avocado. In a second phase, an in vitro propagation method using zygotic embryos for avocado breeding purposes was optimized. A procedure combining zygotic embryo culture and mutation induction is being used for the improvement of salinity, drought, and root-rot tolerance. Reasonable mutagenic doses (LD50 = 21, 27 and 28 Gy) were determined for 'Duke-7', 'Catalina' and 'Hass' cultivars, respectively, and selective doses (LD20 = 157 mM of NaCl, LD50 = 6% PEG-6000) were established for salinity in 'Duke-7' rootstock. In addition, a morphological and molecular identification of Phytophthora spp. strains causing root rot in avocado, was undertaken. As part of this work a first report of Phytophthora palmivora Butler causing root rot on avocado in Cuba was obtained and a high morphological variability for those isolates was demonstrated. A conductimetric bioassay was used to measure in a fast way, the response of leaf and root tissues of avocado cultivars challenged by both crude filtrates and zoospore suspension of P. palmivora strains. A differential response was observed between cultivars while roots proved to be the better tissue for in vitro identification of putative resistance. A set of M1 mutant lines is currently being evaluated for tolerance/resistance to salinity and rootrot under controlled environmental conditions.