Abnormal haematology parameters in patients with HIV / AIDS are common. Anaemia is a frequent complication among these patients and it is usually associated with serious complications. Neutropenia and eosinophilia are common in the advanced stages of AIDS. It is therefore important to determine the haematology parameters in HIV /AIDS patients. This prospective study was carried out between July and September 2008. A total of 113 case notes of HIV / AIDS patients attending the Heduru Clinic were randomly selected. Their certified full blood count electronic results were obtained from the Haematology laboratory in Port Moresby General Hospital. Detailed re-examination of the fixed stained peripheral blood film of each patient was carried out using high-powered microscope. Gender distribution of the 113 case notes indicated 46 (41%) males and 67 (59%) females. Analysis of the data indicated high frequency of anaemia among the patients. Microcytic hypochromic anaemia was prevalence among 47.8% of the patients, macroscopic hypochromic anaemia 29.2% and normochromic normocytic anaemia 23.0%. Blood film showed presence of anisocytosis and poikilocytosis. Although only one patient had leucocytosis, leucopenia was prevalent among 20.4% of the patients; of these mild leucopenia was more frequent than moderate leucopenia. A total of 51 (45.1%) patients had Eosinophilia; of these 76.5% had mild eosinophilia, 17.6% moderate eosinophilia and 5.9% marked eosinophilia. Thrombocytopenia was observed in 21.2% and 0.9% with induced pseudothrombocytopenia. It is hoped that these findings will serve as base line for more detailed studies, and support the need to strongly advocate for routine monitoring of full blood count haematological parameters of HIV/AIDS patients in Papua New Guinean.