Introduction Pharmacotherapy follow-up encourages the effective and safe use of medicines; however, evidence of their efficiency is required to make decisions about their future implementation in the country. Objective : To determine the efficiency of the pharmacotherapy follow-up of polymedicated elderly people in Diez de Octubre municipality , Havana, Cuba. Material and Methods : Cost-effectiveness analysis based on the comparison between pharmacotherapy follow-up of medicines administered at home and pharmacotherapy without follow-up. Social perspective was used to estimate the cost of a negative outcome associated with medication. The direct cost of providing the service was estimated, as well as the economic impact on the consumption of medicines and the use of health services by patients. Results : The patients were mostly women in both groups; the mean age was approximately 75 years and there were 2.02 negative outcomes associated with medication, on average. Twenty-seven of them (42.19%) were resolved, resulting in a reduction in the cost of monthly pharmacological treatment of 65.45 Cuban pesos and a reduction in the health care costs of 465.07 Cuban pesos. Pharmacotherapy follow-up proved to be a cost-saving alternative with a release of 22.71 Cuban pesos for every negative outcome associated with the use of medication. Conclusions: Pharmacotherapy follow-up provided to polymedicated elderly people in a health area in Havana demonstrated to be an efficient technology for the rationalization of therapeutics.