In a group of 245 patients with clinical suspicion of pulmonary embolism we analyzed the ECG for 22 signs that have been associated with this disease. Subsequently, the patients were divided into two groups: those with confirmed embolism and those in whom embolism was not confirmed. The occurrence of the ECG signs was assessed separately for the two groups. Furthermore, we related ECG features to severity of embolism as estimated at lung scan. Tachycardia and S-T depression were the commonest findings in both groups. P-R displacement, late R in a VR, S1Q3T3, S slurred and T inversion in V1-V2 were more frequent in embolic than in nonembolic patients (p less than 0.05 or less). All the above mentioned signs were more frequent at diagnosis than at recovery in embolic patients (p less than 0.05 or less), whereas only tachycardia was more frequent at diagnosis than at control in nonembolic patients (p less than 0.001). S-T depression and T inversion in V1-V2 were also associated to severity of embolism. Since some ECG signs are very frequent or specific in pulmonary embolism, this condition should always be suspected when they are found and, particularly, when previously absent in the same patients and/or not explained by other conditions.