Objectives: This study sought to analyze the outpatient parenteral antimicrobial therapy (OPAT) services provided by a tertiary hospital, in terms of types and duration of antimicrobials administered, and assess whether these services were in line with current good practice recommendations. Methods: The electronic healthcare records of all stable patients with infectious diseases, aged ≥ 18 years, who received OPAT services between January 2019 and March 2021, were analyzed. For statistical analysis, the patients were divided into younger (< 65 years) and older (≥ 65 years) adults and the difference between them, in terms of healthcare resources utilization, was assessed. Results: Over 27 months, 199 patients received OPAT services, resulting in saving of 7514 bed-days. Bone and joint infections (38.7%) were the predominant diagnoses. The median actual OPAT duration was significantly greater than the planned duration for the total study population, younger adults, and older adults (p < 0.050). Of 28 (14.1%) patients with adverse events, 25 were related to antimicrobials while the remaining three were associated with catheters. There were no significant differences between younger and older adults in the characteristics evaluated, except for the higher incidence of Staphylococcus aureus (p < 0.001) and Escherichia coli, Staphylococcal spp., Streptococcal spp., and Pseudomonas spp. (p = 0.003) infection in older adults. Conclusions: The actual median duration of OPAT therapy was significantly longer than planned, with suboptimal adherence to the principles of antimicrobial stewardship. OPAT has been shown to be safe for both younger and older adults.