Abstract Determining the sample size in a scientific investigation is important because it gives reliability in the results together with the efficiency in the use of resources and optimization of time. Polyembryony is a characteristic that allows to obtaining clonal and zygotic plants in the same seed. In mango this characteristic is presented, however, there is no information that mentions which is the adequate sample size to evaluate it. The objective of the present work was to determine the optimum sample size by means of the maximum curvature method for future polyembryony studies. Mangoes from the cultivar Manila and Ataulfo were collected from the states of Guerrero and Nayarit, Mexico. In each state, two orchards of each cultivar were chosen, and in each one three trees were selected. In the Fruit Biotechnology laboratory of the Colegio de Postgraduados, Campus Montecillo, five fruit variables were evaluated: weight of fruit, seeds (endocarp and embryos), embryos, weight of the largest embryo and number of embryos. In all the variables evaluated, except for the weight of the largest embryo, the inflection point of the curve was in 6 fruits and an optimal sample size of 8 fruits was determined. The minimum variation coefficients (CV) for fruit weight were from 17.9 to 19.1%, for seed weight 12.7 to 19.3%, embryo weight 12.3 to 17.1% and number of embryos 6.7 to 16.7%. In the case of larger embryo weight, it was determined that 20 fruits are the optimal sample size, obtaining CV from 7 to 22.6%. The fruit and seed weight characteristics were the least variation, and number of embryos with higher CV. The cultivar Manila of Nayarit presented the highest CV in all the variables studied.