Abstract: Poor management practices may result in poultry having inadequate drinking water for prolonged periods and consequently adverse haematological effects. The effects of water deprivation for up to 48 hours on osmotic fragility of erythrocytes, plasma osmolarity and erythrocyte indices was investigated in eighteen, female Guinea fowl. Six birds had drinking water ad libitum and the other 12 were deprived of drinking water for up to 48 hours. Erythrocyte osmotic fragility was determined in serially diluted phosphate buffered saline. Deprivation of drinking water significantly (p < 0.05, ANOVA) decreased body mass (-7.9 ± 2.4% and -12.8 ± 3.2%, after 24 and 48 hours, respectively) but did not (p > 0.05) affect erythrocyte osmotic fragility. Water deprivation significantly (p < 0.05) increased plasma osmolarity and PCV but decreased the MCV. However, there was no significant difference (p > 0.05) in the osmolarities, PCVs and MCVs of the birds deprived of drinking water for 24 hours compared to those deprived for 48 hours.