The conformational analysis of estrone and its derivatives has been performed using the crystallographic data. It is shown that the estrone backbone may have four different conformers due to the conformational flexibility of the B- and D-rings. The correlation plots describing the conformations of the B- and D-rings are given. There is no apparent correlation between the nature of the substituent at C (3) and the overall conformation of the estrone backbone. An X-ray analysis of 3-deoxyestrone has also been undertaken. The crystal data are: space group P212121, Z = 4(C18H22O), a 25,240 (3), b 8,049 (2), c 7,002 (3) A, V 1423 A3, dcalc 1,19 g X cm.-3. The final reliability factors are: R 3,71% and Rw 4,23% for 1501 observed reflections measured on an automatic diffractometer.