Iron deficiency is a common health problem in mammals, especially in growing piglets hence iron administration to suckling piglets is a routine practice in swine production. A total number of 160 weaners were allotted to two experimental groups according to body weight (I -cachectic underweight piglets; II -piglets with appropriate weaning body weight). Additionally, each group was divided into two subgroups, with iron administered to piglets in subgroups IA and IIA on the first day of the experiment. In order to monitor the weight gains in pigs, they were weighed twice. To estimate the haematological status, blood samples were taken on the weaning day from selected piglets (10 in each subgroup). Haematological analyses were conducted using Hb, Ht, RBC, MCV, MCH, MCHC as early anaemia indicators. Additionally plasma iron (PI) and total iron-binding capacity (TIBC) were assessed as parameters of the actual and potential circulating extracellular iron. The aim of the study was to investigate the effect of additional postweaning Fe supplementation on production results. A lower concentration of PI was noted in weaker piglets (Group IA and IB). Throughout the experiment higher daily gains were noted in Group II; differences between Group IIA and IA as well as IB were statistically confirmed at p≤ 0,01. It might be expected that an additional Fe dose applied in weaning piglets can be used as a growth promoter. On the other hand, in case of cachectic animals toxicity of supplemental iron must be taken into consideration. Running title: