The optimal management approach for patients with mild forms of cervical spondylotic myelopathy (MCSM) has not been well established. The aim of the present study was to investigate the outcome of conservative treatment, identify prognostic factors and provide evidence for the timing of surgical intervention. A total of 90 patients with MCSM attending hospital between February 2007 and January 2009 were prospectively enrolled. Initially, all patients received conservative treatment and were followed up periodically. When a deterioration in myelopathy was clearly identified, surgical treatment was conducted. Clinical and radiological factors correlating with the deterioration were examined, and final clinical outcomes were evaluated using the Japanese Orthopedic Association (JOA) score. At the end of January 2012, follow-ups of >3 years were completed. Seventy-eight patients were available for data analysis. Only 21 patients (26.9%) deteriorated and underwent surgery thereafter (group A), while the remaining 57 patients (73.1%) were treated conservatively throughout (group B). Statistical analysis revealed that segmental instability and cervical spinal stenosis were adverse factors for the prognosis of conservative treatment. Although the JOA scores of the patients in group A declined initially, following surgical intervention, no significant differences were identified in JOA scores between the two groups at the time of the final follow-up (P=0.46). In summary, conservative treatment is effective in MCSM patients. Patients with segmental instability and cervical spinal stenosis have a tendency to deteriorate, but conservative treatment remains the recommendation for the first action. If the myelopathy deteriorates during conservative treatment, timely surgical intervention is effective.