The methadone maintenance treatment (MMT) has been initiated in Wuhan, China since early 2006. To understand the social-demographic, behavioral, and infectious diseases characteristics of drug users enrolled in their first-ever-MMT between 2006 and 2015, a retrospective observational study was implemented to also provide evidence for health policy-decisions to reduce harm and control disease. Pearson chi-square tests and t-tests were used to assess significant differences between two 5-year periods, 2006-2010 and 2011-2015. We observed increases in the mean age (38.65 vs. 42.43 years, P < 0.001), mean age of initial opioid drug use (28.18 vs. 31.07 years, P < 0.001), employment (11.9% vs. 30.7%, P < 0.001), married/co-habiting (42.4% vs. 47.8%, P < 0.001), and declines in higher education level (93.6% vs. 84.8%, P < 0.001), injection (82.3% vs. 75.1%, P < 0.001), syringe sharing (27.7% vs. 9.9%, P < 0.001), HCV infection rates (72.9% vs. 70.5%, P = 0.017). The number of drug users enrolling each year reduced following a continuous rapid growth in the first 3 years. The findings imply for adjusting in treatment services and allocation of resources to respond to emerging trends. In addition, the data will also be helpful for identifying needs and getting a baseline insight of the social-demographic and behavioral characteristics of the opioid abusers in the area.