The objective of this work was to investigate the effects of vitamin A supplementation on the levels of total serum proteins, albumin, globulins, albumin/globulin ratio, haemoglobin concentration and haematocrit in chickens experimentally infested with Ascaridia galli. One hundred, ISA brown chickens, aged eight weeks, were divided into four equal groups, and, depending on the groups, they were experimentally infected with 350 embryonated eggs of A. galli and daily supplemented with 1500 I.U retinyl acetate. Group I was infested with A. galli alone, group II infested and supplemented, group III neither infested nor supplemented and group IV was supplemented with vitamin A alone. The results show that chickens that were infested with A. galli alone (Group I) had significantly lower values of the measured parameters than the non infested (group III). However, levels of globulin were not statistically different between the two groups. Similarly, group II (Infestation with supplementation) had significantly lower values of total serum proteins, albumin, globulin), albumin/globulin ratio, haematocrit and haemoglobin than group IV (Non infested and supplemented). On the other hand group I (Infestation alone) had significantly lower values of the above mentioned parameters than group II (Infestation with supplementation) (P<0.005). Similarly, group IV (supplemention alone) had significantly higher values than group III (non supplemented). It is concluded that A. galli  infestation lowers serum total proteins, albumin, albumin/globulin ratio as well as  haemoglobin concentrations, haematocrit and body weight, and that, vitamin A supplementation improves the levels of the above mentioned parameters.