Research on sex ratios of Lewy body dementia is controversial, established in small samples, and rarely focused on prodromal stage. The objective is to investigate the clinical sex ratios (men/women) and their associations with clinical features among individuals with mild cognitive impairment with Lewy bodies (MCI-LB), dementia with Lewy bodies (DLB), Parkinson's disease with mild cognitive impairment (PD-MCI), and Parkinson's disease with dementia (PDD) in China.We conducted a multicenter cohort study, including 1038 individuals with probable MCI-LB, DLB, PD-MCI, or PDD diagnosis from 22 memory clinics in China from January 2018 to March 2022, and recorded their demographic and clinical data by reviewing medical records. Descriptive and regression analyses were used to calculate the sex ratio (men/women), and its associations with demographic and clinical data.In this study, men comprised 35.14% (men/women sex ratio = 0.54) for MCI-LB, 46.72% (men/women sex ratio = 0.88) for DLB, 63.56% (men/women sex ratio = 1.74) for PD-MCI, and 52.40% (men/women sex ratio = 1.10) for PDD. Sex ratios roughly increased with age. Men had more parkinsonism (p = 0.000) and less fluctuating cognition (p = 0.024) in MCI-LB, and those with PD-MCI had more RBD (p = 0.001). Women with PD-MCI had lower MMSE scores (β ± standard error =  - 1.24 ± 0.58, p = 0.04), more irritability (0.95 ± 0.46, p = 0.04) and fluctuating cognition (- 3.41 ± 1.31, p = 0.01), and less parkinsonism (- 2.10 ± 0.97, p = 0.03) than men after adjusting for demographic and cardiometabolic conditions.There were more women in DLB and MCI-LB, and more men in PD-MCI and PDD. The sex distribution, demographic, and clinical characteristics differed, which strengthened the independence and heterogeneity of the four diseases, and indicated sex-sensitive strategies for management of dementia necessary.© 2022. The Author(s).