Unilateral spinal anesthesia (USpA) is a technique used to restrict the effect of the spinal block on the operative side. 10–15 degrees reverse Trendelenburg position has been used to control the height of the spinal block using hyperbaric drugs. We aimed to study the effect of the 10-degree reverse Trendelenburg position on the quality of block and hemodynamic stability in unilateral spinal anesthesia in this hospital-based, double-blind, randomized clinical trial. 60 patients of both sexes between 20–60 years of age, undergoing below-knee orthopedic surgeries, were randomized into 2 groups. In both groups, spinal anesthesia was given with 2 mL bupivacaine heavy (0.5%), and the lateral position was maintained for 10 mins. Group 2 patients were kept in a 10-degree reverse Trendelenburg position throughout the surgery. The hemodynamic parameters and block characteristics of the two groups were compared using Epi Info statistical software. The onset of sensory block was faster in Group 1 (recumbent) compared to Group 2 (reverse Trendelenburg). The two-segment regression time was longer in the second group. In group 2, 73.3% of patients reached a level at T8 or below T8, compared to 46.7% in Group 1. The duration of sensory block and anesthesia was longer in Group 2. We conclude that reverse Trendelenburg of 10 degrees immediately after spinal anesthesia significantly limits the level of sensory block and prolongs the duration of unilateral spinal anesthesia.