This research aimed at investigating how the experience of trauma can influence the psychological correlates of long-COVID over time in a clinical sample of patients hospitalized because of COVID-19. Through a longitudinal research design, 70 post-acute patients with COVID-19 were followed-up after hospital discharge in 3-time points up to 6 months and completed the Post-traumatic Stress Disorder Checklist for DSM-5 (PCL-5) and the Symptoms Checklist-90-Revised (SCL-90 R). Repeated measures mixed models with random intercept were used to evaluate the effect of trauma (yes/no) over time (T1, T2, T3) on the SCL-90-R scales. Results showed that patients with trauma display significantly worse psychological outcomes in all the SCL-90-R dimensions [all p < .05 for the principal effects of trauma(y)], especially in symptoms of depression [time 2 vs time 1trauma(y): b = -3.86, 95%CI (-7.18, -0.53), p = .035; time 3 vs time 1trauma(y): b = -4.77, 95%CI (-8.10, -1.45), p = .011], anxiety [time 3 vs time 1trauma(y): b = -4.54, 95%CI (-7.72, -1.37), p = .011], and obsessive-compulsive difficulties [time 3 vs time 1trauma(y): b = -4.03, 95%CI (-7.20, -0.86), p = .027]. These findings shed light on the long-term psychological consequences of COVID-19 among hospitalized patients and highlight the key role of trauma, suggesting its assessment to tailor psychological interventions.