There is little information available about the true incidence of post-thrombotic syndrome (PTS) after pulmonary embolism (PE). The aim of this study was to investigate the incidence of PTS in patients with previous pulmonary embolism without concomitant ultrasonographically-detectable deep vein thrombosis (DVT). A retrospective cohort study was conducted at a single tertiary care centre, Cosenza, Italy. Forty-seven consecutive patients with proved PE without DVT within the previous 2 to 6 years, 45 patients with previous DVT in the same years, and 45 patients with diseases unrelated to venous thromboembolism (VTE) underwent a blind assessment for PTS using a clinical score. Two of 47 (4.2%, 95%CI: 0.01-9.9) patients with PE, 2 of 45 (4.4%, 95%CI: 0.01-10.4) patients with diseases unrelated to VTE, and 23 of 45 (53.3%, 95%CI: 38.7-67.9) patients with DVT showed signs and symptoms of PTS. The difference between the first two groups was not statistically significant (p = 0.7). In conclusion, the incidence of PTS after pulmonary embolism without DVT is low, and no different from that of patients without previous VTE.