Objectives: In Canada, a 13-valent conjugate polysaccharide pneumococcal vaccine (PCV13) has recently been licensed for immunocompetent adults aged 50 years or older, as well as children over the age of 5. Currently, a 23-valent pneumococcal polysaccharide vaccine (PPV23) is recommended for high risk adults and all seniors. The health benefits and economic value of vaccinating Canadian adults with PCV 13 instead of PPV 23 is unknown. Compared to PCV13, PPV 23 covers 11 additional serotypes but may not be as effective for the 12 shared serotypes due to PCV13 being a conjugate vaccine as opposed to a polysaccharide. The objective is to develop a model that compares the health and economic consequences of PCV13 as compared to PPV23 in Canadian adults aged 50+. Methods: We developed a base simulation model for an entire population of providing PCV13 to children less than 2 years of age and simulating the herd effects to the greater population. Vaccinating adults older than 50 years of age with either PCV13 or PPV23 was then compared to the base model, and the health and economic consequences examined across each scenario. Health impacts included invasive pneumococcal disease and pneumococcal related disease. Invasive disease is caused by Streptococcus Pneumococcal and is clinically presented as: meningitis, bacteremia and invasive  pneumonia. Pneumococcal related disease is non invasive and has many different etiologies, the main clinical presentations include: otitis media (in base model for children only), and non-invasive pneumonia. Costs and QALYs were contrasted between the two adult vaccination strategies. Results:  Compared to PPV23, PCV13 was associated with 0.278more cases of invasive  pneumonia, 0.061more cases of bacteremia, 0.002more cases of meningitis,  and 27.997less cases of pneumococcal related disease per 100,000. Compared to PPV23, the incremental cost effectiveness ratio associated with PCV13 was $10,028 per additional QALY gained. Conclusions: Compared to PPV23, vaccinating adults with PCV13 is cost effective.