Since a lack of financial security among vulnerable groups could further hamper health and well-being, this study scrutinises factors predicting rejected prolonged sickness cash benefit claims among people on compensated sick leave of more than 180 days with a rejection between days 181 and 365. All 246,872 claims for employed people on sick leave recorded in the Swedish official statistics register between January 2018 and June 2021 were analysed. Claim outcome was evaluated using logistic regression with odds ratios recalculated to relative risks (RR) with 95% confidence intervals (CI), mutually adjusted for sociodemographic, work and health-related factors. Overall, 46,611 (19%) of the claims were rejected, with slightly lower rates among women (RR=0.97; 95% CI 0.95-0.99). Musculoskeletal diseases had the highest rejection rates (RR=1.84; 95% CI 1.75-1.94) followed by injuries (RR=1.57; 95% CI 1.50-1.64) and symptoms (RR=1.51; 95% CI 1.46-1.56). Mental disorders also had above-average rates (RR=1.14; 95% CI 1.09-1.19), whereas the lowest rates were found among pregnancy-related diagnoses (RR=0.13; 95% CI 0.12-0.14) and neoplasms (RR=0.18; 95% CI 0.18-0.18). Higher rates were found among immigrants (RR=1.37; 95% CI 1.34-1.40), those with only primary education (RR=1.09; 95% CI 1.06-1.12) and among blue-collar workers. The regional variation was substantial (RR range 0.41-1.72). High rejection rates were found for complex diagnoses and diagnoses with presupposed work ability in physically lighter occupations and among groups with assumed precarious positions at the labour market. Systematic differences in rates were identified between geographic regions. More studies are warranted to conclude if the differences found could be justified by other factors.