Despite a growing volume of literature on post-intensive care syndrome, we know little about how subjective symptoms affect intensive care unit survivors in the long term. This study aimed to elucidate the prevalence of subjective symptoms and to determine the clinical importance of post-intensive care syndrome by evaluating the association between these symptoms and psychiatric symptoms. We evaluated new-onset or worsening subjective symptoms and psychiatric symptoms in 81 patients at 3 months after discharge from an intensive care unit. More than half of patients had at least one subjective symptom, such as weakness (n=31), fatigue (n=23), malaise (n=14), body pain (n=14), or insomnia (n=9). The presence of subjective symptoms is associated with worse psychiatric symptoms (post-traumatic stress disorder, anxiety, and depression) at 3 months after ICU discharge. We found insomnia was particularly strongly associated with psychiatric symptoms in our study group. UMIN Clinical Trial Registry no. UMIN000023743, September 1, 2016.