Abstract. Setyowati A, Sukaya, Yuniastuti E. 2018. Morphological and cytological analysis of yellow skin dragon fruit (Selenicereus megalanthus). Cell Biol Dev 2: 8-14. Dragon fruit is a tropical fruit that has the potential to be developed. Information on morphological and cytological characters of dragon fruit plants is still small and simple, so morphological and cytological analysis is necessary. The morphological and cytological analysis yielded useful information to support the dragon fruit plant breeding program. This study aims to study the morphological and cytological characteristics (karyotype) of the yellow skin dragon fruit (Selenicereus megalanthus (Schum. ex Vaupel) Moran). This study took samples from "Kusumo Wanadri Agrotourism" Glagah Indah Beach, Yogyakarta, Indonesia. Chromosomal identification was carried out at the Plant Breeding Laboratory, Faculty of Agriculture, Universitas Sebelas Maret, Indonesia. The research was carried out from December 2006 to June 2008. The methods used were field observations and treatment methods in water for 24 hours at a temperature of 5-8ºC, fixation in 45% acetic acid solution for 2 hours at a temperature of 5-8ºC, and hydrolysis in an aqueous solution. One (1) N HCl for 3-4 minutes at 60ºC, staining in 2% aceto-orcein solution for 24 hours at 5-8ºC and squashing. Morphological and cytological data were analyzed and presented descriptively. The morphology of the plant S. megalanthus is a white thread-shaped root with a fibrous plant root system. The stem is a smooth, faceted wet stem with concave edges. The fruit is oval, surrounded by short spines, the skin is yellow, and the flesh is white. The S. megalanthus has a tetraploid chromosome 2n = 4X = 44 with a chromosome length ranging from 2 + 0.098 m to 4.75 + 0.98 m. The karyotype formula for the S. megalanthus chromosome 2n = 4X = 44 = 40 m + 4 sm.