Glucose-6-phosphate dehydrogenase (G-6-PD) deficiency is one of the most well known human genetic defects and could possibly result in acute haemolysis after exposure to various oxidative conditions. This work was therefore carried out to determine the incidence of G-6-PD deficiency in anaemic patients attending General Hospital Kafanchan, Kaduna State, Nigeria. The study group comprised of 50 sickle cell, 60 iron deficient and 40 malaria patients, while 50 apparently healthy individuals served as control. Statistical analyses of the results according to age group, sex, marital status, packed cell volume (PCV) values, G-6-PD activities and genotype revealed 24 (12%), 26 (13%) and 6 (3%) were G-6-PD deficient in sickle cell, iron deficiency anaemia and apparently healthy, respectively. G-6-PD deficiency was absent in all malaria patients screened. In terms of marital status, singles of both males and females recorded higher deficiency than their married counterpart (P < 0.05). Furthermore, the age interval of 0 to 10 years old recorded highest number of G-6-PD deficient subjects in all the anaemic patients (P < 0.05). The study therefore suggests the need for routine G-6-PD screening test on anaemic patients to avoid factors which could further precipitate haemolytic crisis.