Leiomyomata represent the most common gynaecological tumour in women of reproductive age, and are the primary indication for hysterectomy in the USA. Cytogenetic and genetic studies have, in recent years, advanced our understanding of the aetiology of these tumours. Cytogenetic aberrations involving chromosomes 6, 7, 12 and 14 constitute the major chromosomal abnormalities seen in leiomyomata, and suggest the possibility that disruption or dysregulation of the genes HMGIC and HMGIY may contribute to the development of these tumours. Based on the finding of a variety of chromosomal aberrations detected in fibroids, other genes with fundamental roles in the pathobiology of uterine leiomyomata await identification. Furthermore, the incidence of fibroids has been shown to be greater in African-American women than in Caucasian women. The existence of a heritability component of uterine leiomyomata has been further implicated by twin-pair studies and the existence of familial forms of leiomyomata, both of which suggest an inherited diathesis for leiomyomata formation. This paper will review the cytogenetic aberrations and gene expression, with respect to their contributions to the pathogenesis of leiomyomata, and also summarize the current understanding of heritability of these tumours.