We conducted a qualitative study to understand user perceptions, acceptability and engagement with an interactive SMS reminder system designed to improve treatment adherence for patients with tuberculosis (TB). Patients received daily reminders and were asked to respond after taking their medication. Non-responsive patients were sent up to three reminders a day. We enrolled 30 patients with TB who had access to a mobile phone and observed their engagement with the system for a one-month period. We also conducted semi-structured interviews with 24 patients to understand their experience with the system. Most patients found the reminders helpful and encouraging. The average response rate over the study period was 57%. However, it fell from a mean response rate of 62% during the first ten days to 49% during the last ten days. Response rates were higher amongst females, participants with some schooling, and participants who had sent an SMS message the week prior to enrolment. Non-responsiveness was associated with a lack of access to the owner of the mobile phone, problems with the mobile phone itself and literacy. Our pilot study suggests that interactive SMS reminders are an acceptable and appreciated method of supporting patients with TB in taking their medication.