The angle formed between the femoral neck and shaft is referred to as the collodiaphyseal angle. In man, the angle decreases during growth and is frequently different in the right and left limbs. This study examines the collodiaphyseal angle in another biped, the growing fowl. Three groups (A, B and C) of growing fowls were examined. The weight difference between birds would alter the forces applied to the growing proximal femur and at the end of the experimental period the birds in group B weighted three times those in group A. Nevertheless, in all three groups the collodiaphyseal angle decreased from 120 degrees to 108 degrees over the growth period. Where there was a difference in collodiaphyseal angle between right and left limbs the angle was more frequently greater in the right. Bodyweight apparently had little effect on the development of collodiaphyseal angle in the fowl, possibly due to the trocharteric/antitrocharteric articulation reducing the stresses applied to the femoral neck.