OBJECTIVES:  The Total Parenteral nutrition (TPN) had several related and complications. The pharmacist had the key role to prevent these problems. The aim of the study to assess the clinical and economic outcomes of pharmacist intervention in Parenteral Nutrition at public hospital in Riyadh city, Saudi Arabia METHODS:  Cohort prospective analysis of 12-month 2015 of pharmacist intervention through TPN services provided to neonates, pediatrics, and adults patients. The TPN services 8-hours per day and 7-days per a week. It was at 300-Bed public Hospital at MOH in Riyadh, Saudi Arabia. The pharmacist reviews and prepared TPN. The pharmacist intervention documented TPN-related problem before TPN preparations. The pharmacist intervention used an International Study Model (Kinky et al., Ann Pharmacother 1999), measure level of activity, rational of clinical intervention, recommendation, patient outcome and PharmacoEconomic impact RESULTS: The total number pharmacist intervention 402 of identified TPN-related problems. The total number of TPN orders was 394 prescribed to 82 patients. Of those intervention 209 (51.99%) was male, 193 (48.01%) was female. The majority of them in neonates 303 (75.56%) followed by Pediatrics 97 (24.19%). The highest TPN interventions were potentially significant 174 (46.4%) and potentially serious 108 (28.8%). The rationale of intervention was inappropriate dose 119 (31.7%) drug therapy omission 60 (16 %) and inappropriate route of administration 41 (10.9 %). The most patient outcome was laboratory value improved 170 (45.33%), and patient condition improved 137 (36.53%). The most PharmacoEconomic impact was the patient length of hospital stay decreased 226 (60.27%) and reduction in the cost drug therapy monitoring 79 (21.07%). The total annual estimated cost avoidance (689,190.89 USD) CONCLUSIONS:  TPN clinical pharmacist had an essential vital role of preventing a TPN-related problem, improve patient outcome, and avoid the unnecessary additional cost. Expanding TPN clinical pharmacist mandated for all TPN services at all health care system in Saudi Arabia.