<b>OBJECTIVE:</b> To study the impact of Helicobacter pylori (HP) infection on motor function, gastrointestinal symptoms, and quality of life in a large cohort of Parkinson Disease (PD) patients. <b>BACKGROUND:</b> Some studies have suggested that chronic Helicobacter pylori infection can aggravate the neurodegenerative process in PD, and targeted intervention could potentially modify the course of this disabling disease. <b>DESIGN/METHODS:</b> 102 consecutive PD patients underwent 13C urea breath testing and blinded evaluations consisting of the Unified Parkinson’s Disease Rating Scale (UPDRS) including “On”-medication motor examination (Part III), objective and quantitative measures of bradykinesia (Purdue Pegboard and timed gait), Leeds Dyspepsia Questionnaire, and PDQ-39 (a health-related quality of life questionnaire). <b>RESULTS:</b> 32.4[percnt] of PD patients were HP-positive. HP-positive patients were older (68.4±7.3 vs. 63.8±8.6 years, P=0.009) and had significantly worse motor outcomes; UPDRS Part III (34.0±13.0 vs. 27.3±10.0, P=0.006), Pegboard (6.4±3.3 vs. 8.0±2.7 pins; P=0.012) and timed gait (25.1±25.4 vs. 15.5±7.6 seconds; P=0.042). In multivariate analysis, HP status demonstrated significant main effects on UPDRS Part III and timed gait. The association between HP status and these motor outcomes varied according to age. Indigestion and burping were more common among HP-positive patients. PDQ-39 Summary Index scores did not differ between the two groups. <b>CONCLUSIONS:</b> This is the first and largest cross-sectional study to demonstrate an association between HP positivity and worse PD severity in relation to both motor and gastrointestinal symptoms. Properly designed treatment trials are needed to investigate the causal link between HP infection and PD, and the underlying mechanisms for this. <b>Study Supported by:</b> Malaysian Ministry of Higher Education grants for High-Impact Research (HIR), E000033 and UM.C/625/1/HIR/MOHE/CHAN/11-H-50001-00-A000025 <b>Disclosure:</b> Dr. Tan has nothing to disclose. Dr. Mahadeva has received personal compensation for activities with Janssen Pharmaceuticals, Abbott Laboratories, and AstraZeneca as a speaker. Dr. Thalha has nothing to disclose. Dr. Kiew has nothing to disclose. Dr. Yeat has nothing to disclose. Dr. Ng has nothing to disclose. Dr. Ang has nothing to disclose. Dr. Chow has nothing to disclose. Dr. Loke has nothing to disclose. Dr. Vadivelu has nothing to disclose. Dr. Ibrahim has nothing to disclose. Dr. Yong has nothing to disclose. Dr. Tan has nothing to disclose. Dr. Fox has received personal compensation for activities with Astra Zeneca, Merz, UCB Pharma, Novartis, Teva Neuroscience, Ipsen, and Zambon. Dr. Fox has received research support from Merck Serono and Avanir. Dr. Marras has received personal compensation for activities with EMD Serono. Dr. Lang has received personal compensation for activities with Abbott Laboratories, AbbVie, Allon Therapeutics, Avanir Pharmaceuticals, Biogen Idec, Boehringer Ingelheim Pharmaceuticals, Ceregene, Inc., Eli Lilly & Company, Medtronic, Merck & Co., Novart Dr. Lim has received personal compensation for activities with GlaxoSmithKline and Novartis.