The anti-CD20 chimeric monoclonal antibody rituximab has been effectively used in the treatment of patients with primary immune thrombocytopenia (pITP). We retrospectively evaluated 19 patients affected by pITP resistant to 2 or more lines of therapy who were treated with rituximab. Nine of the 19 patients showed an initial response (47.4%). The sustained response rate was 31.6% (6/19). The median follow-up of the patients was 53.2 months (range 9.2-92.9). Disease-free survival at 48 months was 62.2%. Following rituximab treatment, a proportion of patients (42%) recovered a normal B lymphocyte number. During the follow-up, no opportunistic or severe infectious complications were observed. These data confirm, over a long period of observation, the efficacy and safety of rituximab treatment in the management of patients with resistant pITP.