The objective of this study is to assess the efficacy of an alpha-1 adrenergic receptor blocking agent on the spontaneous passage of proximal ureteral calculi a parts per thousand currency sign10 mm. 92 patients having single radio-opaque proximal ureteral stone a parts per thousand currency sign10 mm were randomized into two groups. Group 1 patients (n = 50) were followed with classical conservative approach and patients in Group 2 (n = 42) additionally received tamsulosin, 0.4 mg/day during 4 weeks follow-up. The stone passage rates, stone expulsion time, VAS score, change in colic episodes, and hospital re-admission rates for colicky pain were compared. The patients were furthermore stratified according to stone diameters < 5 and 5-10 mm. The data of these subgroups were also compared. Stone expulsion rates showed statistically significant difference between tamsulosin receivers and non-receivers (35.7 vs 30%, p = 0.04). Time to stone expulsion period was also shortened in those receiving tamsulosin (8.4 +/- A 3.3 vs 11.6 +/- A 4.1 days, p = 0.015). Likewise, the mean VAS score and renal colic episodes during follow-up period were significantly diminished in Group 2 patients (4.5 +/- A 2.3 vs 8.8 +/- A 2.9, p < 0.01 and 66.6 vs 36%, p = 0.001, respectively). Among the stones < 5 mm, tamsulosin receiving patients had higher spontaneous passage rate (71.4 vs 50%, p < 0.001). The prominent effect of tamsulosin on the 5-10 mm stones was the relocation of the stones to a more distal part of ureter (39.3 vs 18.7%, p = 0.001). Administration of tamsulosin in the medical management of proximal ureteral calculi can facilitate the spontaneous passage rate in the stone < 5 mm and the relocation of the stones between 5 and 10 mm to more distal part of the ureter.