Background: Readmission rates are under growing scrutiny as an indicator of quality of care as much as a potential source of savings. Patients with comorbid psychiatric conditions are more likely to be readmitted, so Consultation-Liaison Psychiatry (CLP) may play a role in lowering readmission rates. Method: In this retrospective cohort study conducted in a general hospital in Paris, France, all consecutive adult inpatients referred for the first time to CLP from January 2008 to December 2016, were included. The main outcomes were 30-day and 7-day readmissions in the same hospital, excluding iterative and planned stays. The objective of this study is to determine whether the timing of psychiatric consultations is associated with 30-day and 7-day readmission rates. Results: A total of 4498 inpatients (2298(51·1%) women, age = 59·8(±19·3) years) were referred to CLP. Adjusting for age, sex, place of residence, year of admission, type of ward, psychiatric diagnosis and disease severity, later consultation was associated with higher 30-day and 7-day readmission rates (adjusted Odds Ratio [95% confidence interval]:1.21[1·10-1·33] and 1·26[1·11-3·13], respectively). Further adjusting for length of stay, the association remained significant for 7-day readmission (1.28[1·05-1·57]). After stratification on the length of stay, for stays in the highest tercile (i.e., >21 days) an intervention after day 3 (versus before) was associated with 30-day and 7-day readmission rates of 15·8% versus 8·6%(1·81 [1·11-3·13]) and 4·9% versus 1·8%(2·98[1·16-9·88]), respectively. Conclusion: Earlier psychiatric consultation was associated with fewer 30-day and 7-day readmissions. Interventional studies are needed to show that proactive CLP teams could help general hospitals to improve quality of care and make significant economic savings.