Direct and maternal variance components and resulting heritabilities were estimated by DFREML-procedures for clean fleece weight (CFW), body weight (BW) and mean fibre diameter (MFD) in the Grootfontein Merino stud. Direct heritabilities were estimated as 0.381, 0.289 and 0.626 for BW, CFW and MFD, respectively. The maternal additive variance estimates were low, resulting in heritability estimates of 0.013 for BW, 0.027 for CFW and 0.012 for MFD. The estimated covariances between direct additive and maternal additive effects (σam) were positive for BW and negative for CFW and MFD. The proportion of σam to the phenotypic variance was 4.0%, –3.1% and –2.4% for BW, CFW and MFD, respectively. It is concluded that the maternal component can be ignored due to its relative small effect on these traits.