Abstract: In vitro study was carried out to investigate levels of oxidative stress indicators of sickle erythrocytes incubated in aqueous extracts of Anacardium occidentale, Psidium guajava and Terminalia catappa for 12 h. At regular time intervals of 3 h, portions of the incubation mixtures were withdrawn and spectrophotometric method was used to assay for levels of erythrocyte Malondialdehyde (MDA) and methaemoglobin (Met. Hb%). The control analysis showed that within the experimental time, erythrocyte MDA increased from 2.45±0.35 to 3.13±0.59 mmol mL-1 (p>0.05; pvalue = 0.801176). Erythrocyte MDA concentrations in the presence of the three extracts were higher than the control samples at t = 3 h (p>0.05; p value = 0.963253). Compared with the control samples at the given time (t) intervals, extract of T. catappa exhibited the highest capacity to cause reduction of erythrocyte MDA ([T. catappa] = 800 mg%; [MDA] = 2.89±0.33 mmol mL-1; t = 12 h). Erythrocyte Met. Hb% increased from 2.42±0.55 to 2.51±0.49% (p>0.05; p value = 0.995171) in the control samples within 12 h. Incubation of sickle erythrocytes with extract of (P. guajava) = 800 mg% for 9 h caused reduction of Met. Hb% from 2.49±0.49 to 2.29±0.45%; p>0.05; p = 0.983519. Extracts of A. occidentale, P. guajava and T. catappa exhibited variable capacities to hinder lipid peroxidation but did not cause corresponding reduction in erythrocyte Met. Hb%, exemplified by negative correlation between the two oxidative stress indicators in the presence of T. catappa and higher concentrations of A. occidentale and P. guajava.