This "proof of concept" study aimed to assess the cost effectiveness of pharmacists giving advice via telephone, to patients receiving a new medicine for a chronic condition, in England. The self-regulatory model (SRM) theory was used to guide development of our intervention and used in training pharmacists to adopt a patient-centred approach. Non-adherence to new medicines for chronic conditions develops rapidly so we developed a study intervention in which a pharmacist telephoned patients two weeks after they had started a new medicine for a chronic condition. Patients were included if they were 75 or older, or were suffering from stroke, cardiovascular disease, asthma, diabetes or rheumatoid arthritis, and were randomized into treatment or control arms. Main outcome measures were non-adherence and cost to the UK NHS, obtained via a questionnaire sent two months after starting therapy. Cost of the intervention was also included. Incremental cost effectiveness ratios (ICERs) were generated. Five hundred patients were recruited. At 4-week follow-up, non-adherence was significantly lower in the intervention group (9% vs 16%, p=0.032). The number of patients reporting medicine-related problems was significantly lower in the intervention group compared to the control, (23% vs 34% p=0.021). Mean total patient costs at 2-month follow-up (median, range) were intervention: pound sterling 187.7 (40.6, 4.2-2484.3); control: pound sterling 282.8 (42, 0-3804) (p<0.0001). The intervention was dominant (less costly and more effective). If the decision maker is not willing to pay anything for one extra adherent patient, there is still a 90% probability that the intervention is cost effective. These findings suggest that pharmacists can meet patients' needs for information and advice on medicines, soon after starting treatment. While a larger trial is needed to confirm that the effect is real and sustained, these initial findings suggest the study intervention may be effective, at least in the short term, with a reduced overall cost to the health provider.