Background: The role of the sympathetic nervous system appears to be central in causing pain in complex regional pain syndrome (CRPS). The stellate ganglion block (SGB) using additives with local anesthetics is an established treatment modality. However, literature is sparse in support of selective benefits of different additives for SGB.Hence, the authors aimed to compare the efficacy and safety of clonidine with methylprednisolone as additives to ropivacaine in the SGB for treatment of CRPS. Methods: A prospective randomized single blinded study (the investigator blinded to the study groups) was conducted among patients with CRPS-I of the upper limb, aged 18–70 years with American Society of Anaesthesiologists physical status I–III. Clonidine (15 μg) and methylprednisolone (40 mg) were compared as additives to 0.25% ropivacaine (5 mL) for SGB. After medical treatment for two weeks, patients in each of the two groups were given seven ultrasound guided SGBs on alternate days. Results: There was no significant difference between the two groups with respect to visual analogue scale score, edema, or overall patient satisfaction. After 1.5 months follow-up, however, the group that received methylprednisolone had better improvement in range of motion. No significant side effects were seen with either drug. Conclusions The use of additives, both methylprednisolone and clonidine, is safe and effective for the SGB in CRPS. The significantly better improvement in joint mobility with methylprednisolone suggests that it should be considered promising as an additive to local anaesthetics when joint mobility is the concern.