Objective: To determine factors influencing immediate and medium-term results of Pulmonary Balloon Valvuloplasty (PBV) for pulmonary valve stenosis. Material and Method: Between 1995 and 2001, the authors carried out PBV in 25 consecutive patients. Two treatment outcomes including immediate and medium-term results were analyzed. The immediate results were classified into two groups based on the pulmonary systolic pressure gradient (PG) immediately after dilation: group I with a PG ≤ 35 mmHg and group II with a PG > 35 mmHg. At medium-term follow-up of 6 to 60 months, echocardiographic evaluations were analyzed and divided into two groups: group A with a PG ≤ 25 mmHg and group B with a PG > 25 mmHg. Demographic characteristics and hemodynamic parameters of immediate and medium-term results were compared and analyzed. Results: Immediately after PBV, the right ventricular systolic pressure (RVSP) decreased from 115.3 □ 37.6 mmHg to 67.0 □ 28.5 mmHg (p < 0.001). The pulmonary systolic pressure gradient decreased from 90.4 □ 37.9 mmHg to 39.3 □ 25.6 mmHg (p < 0.001). Nine of the 25 patients (group II; 36%), with incomplete immediate relief of the obstruction, had more symptoms, a higher baseline PG, higher right atrial pressure, higher RVSP, and a higher systolic pressure ratio. Six of the 25 patients (group B; 24%), with suboptimal medium-term results, had a higher right ventricular voltage on the electrocardiogram, higher pre-dilation PG, and higher RVSP. Conclusion: Successful medium-term outcomes following pulmonary balloon valvuloplasty were achieved in 76% of the patients, with a greater success rate (91%) in patients with a lower right ventricular voltage electrocardiogram (R wave amplitude in V1) ≤ 21 mm, a prevalvuloplasty systolic gradient ≤ 90 mmHg, and right ventricular systolic pressure ≤ 125 mmHg.