Objective. The use of TNF inhibitors leads to an increased risk of serious infections in RA. Predicting this risk would facilitate the prevention of serious infections. The objective of this study was to identify which factors are predictive of the increased risk of serious infections in RA patients treated with TNF inhibiting therapy. Methods. Data from the Dutch Rheumatoid Arthritis Monitoring (DREAM) registry of 2044 patients with RA were used for the analyses. Data were censored at stopping TNF inhibitors or end of observation time up to 5 years. Univariate and multivariate analysis of baseline variables was performed using Cox regression with time to the first serious infection as dependent variable. Results. During a follow-up time of 5 years, 128 of 2044 (6.3%) patients developed a first serious infection with a total of 141 serious infections. The incidence rate in the first year after start of TNF inhibiting therapy was 4.57 first serious infections per 100 patient-years and 2.91 per 100 patient-years over 5 years. Age, corticosteroid use, visual analogue scale (VAS) pain, HAQ, tender joint count 28 joints (TJC28) and the presence of comorbidities were significant predictors for developing a serious infection during TNF inhibiting therapy in the multivariate model. Conclusion. Age, corticosteroid use, VAS pain, HAQ, TJC28 and the presence of comorbidities all at baseline were significant predictors for developing a serious infection during TNF inhibiting therapy in RA patients.