The sexual reproduction biology of Alstroemeria was studied histologically. The processes of sporogenesis and gametogenesis were described in relation to the development of the male and female organs. Comparative developmental stages in Alstroemeria take much longer than they do in tobacco. Alstroemeria has the monosporic Polygonum type of embryo sac development. Bicellular pollen is formed, which after germination on the receptive stigma immediately undergoes the mitotic division of the generative cell, thus finalizing gametogenesis. Part of the progamic phase has been studied as well. As early as 12 h after pollination, some pollen tubes enter the micropyle of the ovules. This knowledge is important for the application of post-fertilization ovule culture to rescue abortive embryos during interspecific hybridization. Keywords: Alstroemeria, Alstroemeria, Inca Lily, sporogenesis, gametogenesis, progamic phase.