Whether or not bone marrow biopsies should be performed routinely in patients with skin lesions that show histological features consistent with an indolent B-cell lymphoma [marginal zone lymphoma (MZL) or follicle centre lymphoma (FCL)] has been debated. As no studies have addressed this question for this group of lymphomas, we evaluated the results of bone marrow biopsy examination in 275 patients with histological features consistent with MZL (n = 82) or FCL (n = 193) first presenting in the skin. In the MZL group, two of 82 patients (2%) showed bone marrow involvement, which was the only extracutaneous localization in one of these patients. In the FCL group, 22 of 193 patients (11%) had bone marrow involvement and was the only extracutaneous localization in nine of them. FCL patients with skin lesions and a positive bone marrow had a significantly worse prognosis when compared with patients with only skin lesions (5-year disease-specific survival 63% vs. 95%; P = 0·001). These results indicate that bone marrow investigation is essential for staging patients with a FCL first presenting in the skin. Bone marrow examination appears to have limited value in patients with MZL presenting in the skin.