Introduction: Hospitalization and discharge in older patients are critical and clinical pharmacists have shown to ameliorate risks. Our objective was to assess their benefit as part of the geriatric team regarding rehospitalizations and related outcomes after discharge focusing on general practitioners’ decision to continue or change discharge medication (GPD). Methods: Prospective implementation study with 6-month follow-up in an acute geriatric clinic. Patients ≥70 years with comorbidities, impairments, and a current drug therapy were consecutively assigned to three groups: control group (CG), implementation group (IG), and wash-out group (WG). CG only received medication reconciliation (MR) at admission; IG and their hospital physicians received a pharmaceutical counseling and medication management; during WG, pharmaceutical counseling except for MR was discontinued. We used a negative-binomial model to calculate rehospitalizations and days spent at home as well as a recurrent events survival model to investigate recurrent rehospitalizations. Results: One hundred thirty-two patients (mean age 82 years, 76 women [57.6%]) finished the project. In most of the models for rehospitalizations, a positive GPD led to fewer events. We also found an effect of pharmaceutical counseling on rehospitalizations and recurrent rehospitalizations in the CG versus WG but not in the CG versus IG models. 95.3% of medication recommendations by the pharmacist in the clinic setting were accepted. While the number of positive GPDs in CG was low (38%), pharmaceutical counseling directly to the GP in IG led to a higher number of positive GPDs (60%). Discussion: Although rehospitalizations were not directly reduced by our intervention in the CG versus IG, the pharmacist’s acceptance rate in the hospital was very high and a positive GPD led to fewer rehospitalization in most models.