We have evaluated the feasibility of using the mobile phone short message service (SMS) for symptom monitoring in patients with asthma. All consecutive patients admitted to hospital for asthma during an 11-month period were considered for enrollment (n = 497). Those meeting the inclusion criteria were randomized into a control (n = 60) and intervention group (n = 60). Patients in the intervention group received SMS messages according to a structured workflow, while patients in the control group had no SMS support. In the intervention group, the mean response rate to the messages was 82%. There was an improvement in the Asthma Control Test (ACT) scores in 36 subjects in the intervention group compared to 28 subjects in the control group. There were reductions in the number of nebulizations in 54 subjects in the control group compared to 50 subjects in the intervention group, and reductions in emergency department visits in 57 subjects in the control group compared to 51 subjects in the intervention group. However, none of these differences were significant. There was no reduction in admission rates in either group (P = 0.5). The service was accepted by most patients, but its long-term effectiveness on the management of asthma remains to be determined.