Current diagnostic workup of patients with suspected acute pulmonary embolism (PE) usually starts with the assessment of clinical pretest probability, using clinical prediction rules and plasma D-dimer measurement. Although an accurate diagnosis of acute pulmonary embolism (PE) in patients is thus of crucial importance, the diagnostic management of suspected PE is still challenging. A 60-year-old man with chest pain and expectoration of blood was admitted to the Department of Cardiology, General Hospital in Cuprija, Serbia. After physical examination and laboratory analyses, the diagnosis of Right side pleuropne monia and acute pulmonary embolism was established. Clinically, patient was hemodynamically stable, auscultative slightly weaker respiratory sound right basal, without pretibial edema. Laboratory: C-reactive protein (CRP) 132.9 mg/L, Leukocytes (Le) 18.9x109/L, Erythrocytes (Er) 3.23x1012/L, Haemoglobin (Hgb) 113 g/L, Platelets (Plt) 79x109/L, D-dimer 35.2. On the third day after admission, D-dimer was increased and platelet count was decreased (Plt up to 62x109/L). According to Wells’ rules, score was 2.5 (without symptoms on admission), a normal clinical finding with clinical manifestation of hemoptysis and chest pain, which represents the intermediate level of clinical probability of PE. After the recidive of PE, Wells’ score was 6.5. In summary, this study suggests that Wells’ score, based on a patient’s risk for pulmonary embolism, is a valuable guidance for decision-making in combination with knowledge and experience of clinicians. Clinicians should use validated clinical prediction rules to estimate pretest probability in patients in whom acute PE is being consiered.