Abstract Background An optimal treatment for traumatic anterior shoulder instability (TASI) remains to be identified. A shoulder instability neuromuscular exercise (SINEX) program has been designed for patients with TASI, but has not yet been tested in patients eligible for surgery. The purpose of this study was to investigate and evaluate the feasibility and safety of the SINEX program for patients diagnosed with TASI and eligible for surgery. Methods A feasibility study with an experimental, longitudinal design using both quantitative and qualitative research methods. A total of seven participants underwent the SINEX program, a 12-week exercise program including physiotherapist-supervised sessions. Feasibility data on recruitment, retention, compliance, acceptability and safety was collected through observation and individual semi-structured interviews. Clinical tests and self-report questionnaires were completed at baseline and 12 weeks follow-up. Clinical assessments included apprehension and relocation tests, shoulder joint position sense (SJPS), shoulder sensorimotor control measured by center of pressure path length (COPL) on a force platform, isometric strength measured by Constant Score-Isometric Maximal Voluntary Contraction (CS-iMVC), self-report questionnaires including Western Ontario Shoulder Instability Index (WOSI), Tampa Scale of Kinesiophobia (TSK) and Global Perceived Effect questionnaire (GPE). Results With one participant recruited every 2 weeks, the recruitment rate was 50% lower than expected. Two of seven participants achieved compliance, defined as at least 66% completion of the scheduled home exercises and at least 50% attendance for the physiotherapist supervised sessions. Barriers for successful compliance were (1) inability to take along exercise equipment when travelling, (2) sick leave, (3) holidays and (4) lack of time/busy days. Four adverse events occurred, one of which was related to the intervention (patellar redislocation). All participants expressed satisfaction with the intervention and felt safe during the exercises. All participants improved in the GPE. Change greater than minimal detectable change (MDC) was reported in four participants in some of the outcome assessments. One of the seven participants declined surgery. Conclusion Further assessment is required on several areas before performing an RCT evaluating the efficacy of the SINEX program for patients with TASI considered eligible for surgery. No adverse events suggest that the program is safe, but patients with general hypermobility may need additional adjustments to prevent adverse events in other areas of the body. Trial registration ClinicalTrials.gov: NCT04152304, retrospectively registered