We performed a process evaluation of a nurse-led telemonitoring programme for patients with asthma. The indicators used to evaluate the programme were feasibility, consistency of peak expiratory flow (PEF) tests, compliance and patient satisfaction. Patients in the intervention group received a home monitor in which spirometry results and symptoms could be recorded. They were asked to measure PEF in the morning and evening. A nurse studied the home monitoring data and took stepwise actions in accordance with the intervention protocol. During a 12-month study period, 55 patients were allocated to the intervention group (26 adults and 29 children). Although technical and logistical problems did occur, the dropout rate was low. At least 75% of the PEF manoeuvres were valid for two-thirds of the patients. Compliance with the study protocol was high. The average number of recorded PEF tests was 1.5 per day, which was less than the two tests per day that were required by the protocol. Patient satisfaction was high and, after one year, less than 20% of the participants chose to discontinue their participation. The results indicate that nurse-led telemonitoring for a motivated group of patients with mild to moderate asthma is feasible and reliable, and satisfying to patients.