Bloom's syndrome is a rare autosomal recessive disorder caused by germline mutation of the BLM gene. The objective of this study was to illustrate the clinical, biological and genetic characteristics of this syndrome through Tunisian series. We report in a retrospective study 8 case of bloom's syndrome observed during 20 years.Results:Our patients were 4 males and 4 females issued from 5 families. For all patients, the parents were consanguineous. The age was 13 to 39 years. The telangiectatic erythema was developed in all the patients between 6 months and 2 years old on the cheeks, on the nose, on the lips and the lower eyebrows. The photosensitivity was constant and was complicated by vesicules and bullae for 5 patients who had extensive lesions, three patients noted accentuation of their telangiectasic erythema. An improvement with the age was noticed for the first four patients. The growth deficiency was observed for all patients. It was marked, between -2 and -4 DS (standard deviation). The number of sister chromatid exchange was increased to twelve fold comparatively to normal subjects. Two patients developed a breast cancer; the evolution was fatal in one. Another patient developed a leukaemia, the evolution was also fatal.Conclusion:Bloom's syndrome is a rare genodermatitis. All the patients presented three symptoms: telangiectatic erythema, growth delay and photosensitivity associated with immunodeficiency. There is significant risk of cancer, so that follow up of patients is mandatory.