Sickle cell anaemia (SCA) is associated with acute and chronic inflammation due vascular occlusion which may cause infarctive tissue damage and in turn initiates secondary inflammatory responses that have not been clearly defined. The main objective of this study is to determine the profile of cytokines (Interleukin 2, Interleukin 4 and Interleukin 10) and some acute phase reactants (C-reactive protein and serum amyloid A) in the steady state and vaso-occlusion of SCA. This is a case-control study of SCA patients who satisfied the inclusion criteria. At the onset of vaso-occlusive crisis (VOC), 10mls of venous blood was collected. A second blood sample of the same amount was collected 4 weeks later when patients were pain free (in steady state). Apparently healthy volunteers participated as controls. Serum IL-2, IL-4 and IL-10 concentrations were obtained using immunosorbent assay (ELISA) kit (R&D system inc. Minneapolis, MN). High sensitivity C-reactive protein (hs-CRP) was analyzed using solid phase enzymes-linked immunosorbent assay and serum Amyloid A was analyzed using automated monoclonalpolyclonal solid phase sandwich enzymes immunoassay runs on the Abbott IM instrument. The haematological parameters were analyzed with a Haematology Autoanalyzer (KX-21 Sysmex). The scoring system to evaluate the clinical severity of SCA involved using simple clinicolaboratory parameters. Data was analyzed using SPSS version 16. The Students’ T-test was used to compare means and chi-squared statistics were used for associations between non-continuous variables. Probability of less than or equal to 0.05 was used to define statistical significant. A total of 49 patients comprising 21 paediatrics and 28 adults with diagnosis of SCA and 39 healthy controls comprising 16 paediatrics and 23 adults were studied. The mean ages ±SD of the paediatric SCA patients and controls were 10.9 ± 3.1 years and 9.4 ± 3.2 years (p = 0.171) respectively. The mean ages ±SD of adult SCA patients and controls were 26.7 ± 7.9 years and 27.5 ± 10.3 years (p = 0.772) respectively. The male: female (M: F) ratio for paediatric patients was 1.6:1 while it was reversed for adult SCA (1:1.6). The controls had an M: F ratio of 1:1 for paediatric patients and 1:1.3 for adults. The total severity score of the 49 SCA patients ranged from 1 to 24, with mean ± SD of 4.84 ± 7.1. Approximately 73.5% had mild disease (severity score < 8), 14.3% moderate disease (severity score 8 - 17) and 12.2% severe disease (severity score >17). The distribution was similar for adult and paediatric patients and there was no correlation between age and severity score of all patients in the steady state. Red cell indices with the exception of MCH and MCHC were significantly lower in the steady state of SCA when compared to those of controls in both adult and paediatric patients. White cell and platelet counts were however significantly higher in the steady state of SCA when compared to those of controls in both adult (p < 0.05) and paediatric (p < 0.01) patients. There was no significant difference in the haematological parameters measured in steady state and during VOC of both adult and paediatric patients (p > 0.05). A higher level of IL-2 was observed in the steady state of SCA patients than in controls (p < 0.0001) for both paediatrics and adults, but the level during VOC was significantly higher than that of the steady state (p < 0.05) in paediatric patients only. Interleukin-4 levels did not distinguish between adult SCA patients in the steady state and controls (p > 0.05), but IL-10 levels were significantly higher during VOC when compared to the steady state levels (p < 0.001), which were also higher than levels in controls (p < 0.01) in both aadult and paediatric patients. Interleukin-2 levels did not correlated with any haematologic parameter measured in the steady state, but CRP correlated with WBC count in both adult (r = 0.563; p = 0.002) and paediatric (r = 0.397; p =0.047) patients. Platelet counts correlated negatively with IL-4 levels (r = -0.454; p = 0.039) and IL-10 (r = -0.435; p = 0.049) in adult patients in the steady state. White blood cell and platelet counts were significant higher in patients with moderate/severe sickle cell disease in adult patients (p = 0.025 and p = 013 respectively), but only WBC count showed this difference in paediatric patients (p = 0.016) only. Of the cytokines and acute phase proteins, IL-2 (p < 0.0001) was the only parameter that was significantly higher in moderate/severe sickle cell disease in both adult and paediatric patients and IL-2 was the only cytokine that correlated with CRP (r = 0.15; p =0.025) and SAA (r = 0.30; p = 0.02) in the steady state of both adult and paediatric patients. Interleukin-4 (p = 0.020) and SAA (p = 0.028) were significantly higher in moderate/severe sickle disease when compared with mild disease in paediatric patients. This study shows elevated levels of pro-inflammatory, anti-inflammatory cytokines and acute phase reactants in SCA patients during VOC when compared with the steady state and controls as expected. Platelet count and Il-2 levels were biomarkers of disease severity in both adult and paediatric patients, while SAA and hs-CRP may be useful surrogates for IL-2 in these patients.