BACKGROUND To learn more about the obstetric outcome after initial septum resection and remnant septum (< or =1 cm) resection. METHODS In 94 patients with septate uteri who underwent uterine septum resection, the reproductive efficiency was analysed in a prospective observational study. The reproductive outcome was analysed after initial resection and (if required) consecutive procedures. RESULTS A total of 94 women were enrolled in the study; all had had two or more miscarriages. The septum was completely removed during the first hysteroscopy in 58 (62%) cases. A residual septum was observed in 36 (38%) patients. Subsequent operative hysteroscopy was performed in the cases (29/36; 80.5%) involving repeated miscarriage and unsuccessful conception. The minimum observation time was 24 months. The difference in delivery rate after the first hysteroscopy between those with a normalized uterine cavity (26/58; 44.8%) and those with remnants (7/36; 19.4%) was statistically significant (P < 0.05). In fact, following the normalization of the uterine cavity, 62.1% (18/29) of the patients delivered, as compared with 19.4% of those (7/36) with a residue and Kaplan-Meyer curves revealed a statistically significant difference (P < 0.05). CONCLUSIONS Women with a remnant uterine septum have an increased chance of successful pregnancy with an improved obstetric outcome after normalization of the uterine cavity.