The improvement of vegetatively propagated plants using biotechnology has been limited, although a reliable in vitro plant regeneration system has been available. In this paper, we report chromosomal instability in the in vitro raised plants of Hippeastrum hybridum cv. United Nations. Vigorous callus induction was obtained from bulb-scale explants on MS basal medium supplemented with 2,4-D (2 mg l^-1) and coconut water (10%, v/v). Four weeks old callus was placed on medium added with various combinations of BAP and NAA for regeneration, maximum shoot regeneration was observed in medium containing 2 mg l^-1 BAP and 0.5 mg l^-1 NAA. The in vitro formed shoots were rooted in medium with 2 mg l^-1 of IBA. Somatic embryogenesis (direct) was also observed, and the embryos were formed frequently on scaly leaves of bulb-scale explant. Instead of 2,4-D, somatic embryos were induced on BAP (0.5 mg l^-1), the number was further improved on NAA added treatments, the embryos germinated into plantlets on the same medium. Although the regenerated plantlets looked normal, squash preparation revealed 33 chromosomes. Beside triploids, the regenerated plant also had tetraploid at low frequency accompanied by cells showing aneuploids and aberrant chromosomes.