Previous research has suggested that circulating inflammatory proteins are associated with benign prostatic disease (BPD). This Mendelian randomization (MR) study was conducted to further investigate the causal relationship between 91 inflammatory proteins and BPD. Genome-wide association study (GWAS) summarized data of benign prostatic hyperplasia (BPH) and prostatitis were obtained from the FinnGen Biobank. The latest study offered the GWAS data on 91 proteins related to inflammation. We performed a bidirectional MR to investigate the causal association between inflammatory proteins and BPD. The outcomes of the IVW method indicated that decreased levels of circulating interleukin-17 C (IL-17 C) (OR = 0.92, 95%CI = 0.85-0.99, p-value = 0.0344) were suggestively associated with a higher risk of BPH and elevated levels of interleukin-10 receptor subunit alpha (IL-10RA) (OR = 1.24, 95%CI = 1.05-1.47, p-value = 0.0132) and urokinase-type plasminogen activator (uPA) (OR = 1.13, 95%CI = 1.00-1.28, p-value = 0.0421) were suggestively related to a higher risk of prostatitis. Furthermore, reverse MR revealed that BPH may promote the expression of circulating factors, including natural killer cell receptor 2B4 (CD244) (OR = 1.07, 95%CI = 1.01-1.13, p-value = 0.0192), T-cell surface glycoprotein CD6 isoform (CD6) (OR = 1.07, 95%CI = 1.01-1.13, p-value = 0.0192), and leukemia inhibitory factor receptor (LIF-R) (OR = 1.07, 95%CI = 1.01-1.15, p-value = 0.0163). Moreover, the results of sensitivity analyses indicate that heterogeneity and horizontal pleiotropy are unlikely to distort the findings. The results of this study indicate a potential association between circulating inflammatory proteins and BPD, which may become new diagnostic indicators or drug targets for clinical application in the prevention and treatment of BPD. However, further investigation is required.