The long-term outcome (nine years) of mitral balloon valvotomy in pregnant patients with severe mitral stenosis was investigated. Twenty-three patients with severe, symptomatic (NYHA class III/IV) mitral stenosis underwent mitral balloon valvotomy using an Inoue balloon technique during the second trimester of their pregnancy; mean follow up in 19 patients was 5.1 ± 2.8 years (range: 1 to 9 years). Immediately after valvotomy, the Doppler-derived mitral valve area was increased from 0.90 ± 0.18 to 1.97 ± 0.36 cm2 (p ‹0.0001), and the transmitral mean gradient decreased from 15.7 ± 4.7 to 5.5 ± 1.6 mmHg (p ‹0.0001). Four patients had mild worsening of mitral regurgitation, and six developed insignificant interatrial communication immediately after mitral balloon valvotomy. There was no other morbidity or mortality. The NYHA class was improved from 3 ± 0.1 to 1 ± 0.02 (p ‹0.001). Twenty-two patients had normal deliveries; one cesarean section (week 36) resulted in stillbirth. No developmental abnormalities were seen in the babies. At long-term follow up of mothers, the mitral valve area was 1.8 ± 0.52 cm2; restenosis developed in three patients (16%). One baby died at one week from sudden infant death syndrome, and one at eight months from pneumonia. The other children showed normal growth, development and speech for their age. In conclusion, mitral balloon valvotomy using the Inoue balloon technique can provide satisfactory immediate relief and long-term outcome to pregnant patients with severe mitral stenosis.