Selection in the CAMDA breeding group for Welsh Mountain sheep has been based since the start of the scheme on an index that includes litter size, maternal ability, lamb growth and mature size. Since 1987 fat and muscle depths have also been recorded in candidate replacement rams by ultrasonic scanning. Current consumer pressure to improve carcass quality suggests that emphasis be placed on developing an index that incorporates scanning results with other production traits. Construction of such an index requires estimates of the genetic and phenotypic correlations between traits in the selection objectives and criteria. Analyses were conducted to estimate these parameters based on data recorded in the nucleus of the CAMDA breeding group.