We cloned partial cDNA sequences of rabbit 17β-hydroxysteroid dehydrogenase 1 (17β-HSD1) and 17β-HSD7. We analyzed the tissue distribution of 17ß-HSD7 as well as the expression in corpus luteum and endometrium during pseudopregnancy. The obtained cDNA sequence of 17β-HSD7 coded for all functional regions of the protein and showed 86 and 81% similarity to human and rodent sequences, respectively. The partial sequence of rabbit 17β-HSD1 was 76 and 82% similar to rodent and human sequences. By Northern analysis 17β-HSD7 expression was predominantly found in reproductive organs like ovary, oviduct, endometrium, placenta and mammary gland. Substantial expression was also apparent in the heart, stomach and cerebellum. The 17β-HSD1 could be detected in placenta by reverse transcriptase-polymerase chain reaction (RT-PCR), so far. During rabbit pseudopregnancy 17β-HSD7 expression was found to be regulated in corpus luteum as well as in endometrium. In the corpus luteum, strongest expression occurred from d10 to d14 of pseudopregnancy (p. hCG) and was downregulated on d16 p. hCG. In endometrium strongest expression of 17β-HSD7 was found on d6 p. hCG, when the endometrium was differentiated to its implantation permissive status.