Summary. Mean ( \ m=+-\ s.d.) pregnancy length for the 14 llamas in this study was 350 \ m=+-\ 4\ m=. \ 5 days. Plasma progesterone concentrations increased by 5 days after mating and remained elevated (>2\m=.\0ng/ml) throughout most of pregnancy. At about 2 weeks before parturition, plasma progesterone concentrations began to decline, dropped markedly during the final 24 h before parturition, and returned to basal concentrations (<0\m=.\5ng/ml) by the day of parturition. The combined oestrone + oestradiol-17\g=b\ and oestradiol-17\g=b\ concentrations varied between 6 and 274 pg/ml and 4 and 114 pg/ml, respectively, during the first 9 months of pregnancy. Concentrations increased between 9 months after mating and the end of pregnancy with peak mean concentrations of 827 \ m=+-\ 58 (s.e.m.) pg oestrone + oestradiol-17\g=b\/ml(range: 64\p=n-\1658) and 196 \ m=+-\ 10 pg oestradiol-17\g=b\/ml(31\p=n-\294)during the last week of pregnancy. Concentrations then declined to 87 \ m=+-\14 pg oestrone + oestradiol-17\g=b\/ml(7\p=n-\488) and 25 \ m=+-\5 pg oestradiol17\g=b\/ml (2\m=.\5\p=n-\142)during the first week postpartum. Plasma cortisol concentrations varied between 2\m=.\6and 51\m=.\9 ng/ml (14\m=.\0 \ m=+-\ 0\m=.\5) from mating until 2 weeks before parturition when the concentrations began to decline. Only a slight increase in plasma cortisol concentrations was observed in association with parturition. Plasma triiodothyronine concentrations varied between 0\m=.\5and 4\m=.\5 ng/ml (1\m=.\9 \m=+-\ 0\m=.\1)throughout pregnancy and the periparturient period. Plasma thyroxine concentrations varied between 21\m=.\3and 91\m=.\5ng/ml (56\m=.\5\ m=+-\ 0\m=.\8) from mating until about 39 weeks of pregnancy when they began to decline, from 43\m=.\0 \ m=+-\ 5\m=.\3 ng/ml at 15 days pre partum to 23\m=.\5\m=+-\ 5\m=.\5 ng/ml immediately before parturition, but then increased to 52\m=.\8\ m=+-\ 3\m=.\9 ng/ml by 1 day post partum.