The objective of study was conducted on to compare immunoglobulin (Ig) concentrations in calves raised under organic and conventional conditions. 30 newborn Holstein Friesian calves (15 rose under organic and 15 under conventional conditions) in two dairy cattle farms. Blood samples were taken from 30 newborn calves at birth (before taking colostrum) and on 1.4th day to compare immunoglobulin (Ig) concentrations in calves raised under organic and conventional conditions. Furthermore, blood and colostrum samples were also taken from the mothers included into the study. IgG and IgM concentrations in colostrum and blood serums were determined using commercial ELISA kits. IgG concentrations at birth (0.79 +/- 0.34, 1.64 +/- 0.95 mg/mL) and on the 14th day (46.5 +/- 21.5, 70.5 +/- 27.8 mg/mL) in calves raised under organic conditions were lower than those raised under conventional conditions (p<0.01). Calves raised under organic conditions also had lower IgM concentrations than calves raised under conventional conditions at birth (0.23 +/- 0.03 and 0.28 +/- 0.11 mg/mL, respectively) and on the 14th day (2.76 +/- 0.56 and 4,30 +/- 1.03 mg/mL, respectively) (p<0.05, p<0.01). IgG concentrations in the blood serum of cows raised under conventional conditions were higher than those raised under organic conditions (p<0.01), while no difference was found with respect to IgM concentrations (p>0.05). No difference was found in the IgG and. IgM concentrations of colostrum obtained from cows raised under organic and conventional conditions. In both the husbandry systems, positive and significant (p<0.01) correlations were found between the Ig concentrations of the mothers and offsprings: Consequently, it can be suggested that higher Ig concentrations in cattle raised under conventional conditions might be due to poorer environmental conditions.