Salivary and serum levels of estradiol and progesterone were measured by radioimmunoassay in 10 Chinese women during their normal menstrual cycles. Changes in salivary estradiol and progesterone levels followed a similar pattern to that in the serum. Significant correlation was found between salivary and serum levels of estradiol and progesterone (p less than 0.001). Measurements of these salivary steroids may be used to assess follicular dynamics. Moreover, salivary sampling is simple, convenient and stress free.