Callus cultures from cotyledon and hypocotyl explants of a Spanish cultivar of melon ('Amarillo Oro') have been tested for their growth and morphogenic capacity on a series of media with different concentrations of indole-3-acetic acid (IAA) and 6-furfurylaminopurine (kinetin). Melon tissues were able to undergo morphogenesis both via organogenesis and embryogenesis, depending on culture conditions and explant source. Shoot buds were obtained at high rates in cotyledon explants. In response to 1.5 mg/1 IAA and 6.0 mg/1 kinetin, more than 90% of the calli produced well-developed shoots. Hypocotyls failed to form shoots but formed somatic embryos on auxin containing media while cotyledon explants usually gave abundant shoots but only rarely formed embryos. It was possible to maintain organogenic callus lines for at least 12 months under defined conditions. Plants were recovered from adventitious shoots produced both in cotyledon-derived calli and from organogenic cell lines.