Primary myelofibrosis and paroxysmal nocturnal haemoglobinuria (PNH) are uncommon clonal blood disorders that are rarely found together. We report a case of primary myelofibrosis (PMF) with concomitant subtle PNH in a 42-year-old man who presented with a 4-week history of fatigue, unexplained chest pain, and new-onset erectile dysfunction. Bone marrow biopsy showed severe fibrosis consistent with PMF. However, smooth muscle dystonia symptoms in the form of new-onset erectile dysfunction and oesophageal spasm were not fully explained by PMF but were clues for PNH, confirmed by flow cytometric assays. Routine PNH testing for patients with new-onset PMF and clinical symptoms suggestive of PNH, as well as those with refractory anaemia despite effective therapy, is crucial since these two conditions can coexist. As a result, a lack of early testing may cause a delay in diagnosis, increasing the patient’s transfusion load and the facility’s costs.