To investigate the frequency of deficiency of spleen qi (DSQ) in persons with Parkinson disease (PD) as well as the correlation between DSQ and PD.This study comprised three parts: determining the frequency of DSQ in participants with PD; comparing the frequency of DSQ in PD and non-PD participants; and monitoring DSQ in participants with PD for 24 weeks. Outcome measurements were a modified DSQ scale and the Chinese version of the Parkinson Disease Questionnaire 39 (C-PDQ39).A total of 187 participants with PD (mean ages 69.9 ± 9.6 years) completed the assessment in Part 1. Of these, 170 (90.9%) were diagnosed as having DSQ. Thirty non-PD participants (mean ages 66.6 ± 10.2 years) completed the assessment in Part 2. Of these 11 (36.7%) were diagnosed as having DSQ. Positive correlations between total DSQ score and Hoehn-and-Yahr (H&Y) stage (correlation 0.316; P < .001), as well as between DSQ and total C-PDQ39 score (correlation 0.572; P < .001), were observed. For Part 3, 47 participants from Part 1 were observed for 24 weeks. Variation in DSQ symptoms was noted, but all participants developed DSQ by the end of the study.DSQ is 2.5 times higher in PD participants than in the non-PD participants. More PD participants had DSQ in the advanced H&Y stages. A larger study is needed to validate these results on the prevalence of DSQ in persons with PD.