Hand spasticity with a flexor pattern is a common problem affecting stroke patients and can result in pain, contractures, esthetic concerns, skin maceration, and overall loss of function. Poststroke (≥6 months) hemiparetic adult patients having a Modified Ashworth Scale (MAS) score of ≥1 for metacarpophalangeal flexion and thumb adduction spasticity were selected to receive an ultrasound-guided 20% ethyl alcohol block performed perineurally at the level of the deep branch of the ulnar nerve. Their MAS scores were evaluated pretreatment at 1 month and the change in MAS scores was assessed using Wilcoxon's test. The threshold for statistical significance was set at p < 0.05. The mean MAS score for the flexor muscles of the 5 MCP joints and for thumb adduction was reduced from 3.3 ± 0.5 at pretreatment to 0.9 ± 0.5 at 1 month after the injection for the 10 patients. One month after the injection, the MAS scores were significantly reduced compared with those at pretreatment (p < 0.001), without complications. These are encouraging results showing that ultrasound-guided alcohol blocks of the deep branch of the ulnar nerve are safe and can help chronic stroke patients with metacarpophalangeal flexion and thumb adduction spasticity at 1 month.