[en] The review describes several experiments conducted to characterize important reproductive parameters in alpacas and llamas. Nuclear techniques such as radioimmunoassay for measuring levels of reproductive hormones have provided comprehensive knowledge of various reproductive functions and aided the design of rational breeding systems. Profiles of the major steroid hormones and prostaglandins as well as the gonadotrophic hormones in milk, blood plasma or urine have been used to monitor normal ovarian activity and heat symptoms, ovulation, luteal activity in non-pregnant females and following fertile mating, maternal recognition of pregnancy, early embryo death, pregnancy, parturition, post-partum and pregnancy diagnosis in the female. In the male, plasma testosterone levels were determined in an attempt to define the seasonality of reproduction of these domestic animals in the Southern Hemisphere. (author). 39 refs, 3 figs, 7 tabs