A variety of systemic autoimmune disorders have been reported in patients with myelodysplastic and myeloproliferative syndromes. A possible association with polymyalgia rheumatica and giant cell arteritis has also been recognised. We report another case of polymyalgia rheumatica and one of giant cell arteritis associated with a myelodysplastic syndrome and the two first cases of giant cell arteritis associated with essential thrombocytaemia and chronic myelomonocytic leukaemia, respectively. It seems that there is a relationship between these entities, but the nature of this association is still unknown.