Objectives: The basis of the estrogen threshold hypothesis formulated by Barbieri is that tissues vary in their sensitivity to estradiol and that a concentration of estradiol between 30 to 45 pg/ml is sufficient for preventing bone loss having  no impact on the bone mineral density (BMD). A novel estrogen free contraceptive containing 4 mg drospirenone (Slinda®)has been developed with a 24+4 regimen to improve cycle control showing a pearl index of 0,7. The objective of this study was to investigate the hormonal development of estradiol after 2 cycles of use to demonstrate that no impact on bone mineral density will be observed. Design and Methods: Twenty-seven healthy volunteers with proven ovulatory cycles were treated with the drospirenone-only pill for two 28-day cycles. Follicular diameter, endometrial thickness, and serum estradiol (E2) and progesterone concentrations were measured and Hoogland scores were determined to certify inhibition of ovulation. Hormonal values were analyzed continuously in both cycles between the day 3 of the first cycle and the day 27 of the second cycle Results: The mean values for estradiol were 40 pg/ml on day 3 of cycle 1; 55,2 pg/ml on day 24 of cycle 1 and 62 pg/ml on day 27 of cycle 1. The values for these days in the second cycle were 71,8 pg/ml, 49,23 pg/ml and 62 pg/ml respectively for the days 3, 24 and 27. There was a subgroup of women with levels lower than 51pg /ml during the two cycles analyzed. In this subgroup the values where the following: 36,7 pg/ml on day 3 of cycle 1, 38,8 pg/ml on day 24 of cycle 1, 34,15 pg/ml on day 27 of cycle 1 and 33,75 pg/ml, 39,2 pg/ml and 49,2 pg/ml on the days 3, 24 and 27 of cycle 2. Conclusion: The estradiol levels with  drospirenone were above 30 pg/ml  , equivalent to those reported with  other progestogens like dienogest or desogestrel  indicating  lack of  impacton  BMD. We can conclude that 4mg drospirenone given in a dosing regimen of 24/4 day does not suppress the E2 levels under 30 pg/ml. As this value is the cut off for the bone to start with osteoblastic activity this new progestin only pill can be considered safe for the bone with no negative impact on   bone mineral   density.