Selected members of the rat alpha 2u-globulin gene family are expressed in several tissues, manifesting characteristic developmental and endocrine transcriptional control. Studies are now underway to identify the responsible cis sequences and transacting factors. We recently reported that the cloned rat alpha 2u-globulin 207 gene manifests tissue-specific androgen-dependent expression; it is expressed in livers of male, but not female, transgenic mice. In the present study a portion of this gene (-639 to +1395) is used as an in vitro template in the presence of nuclear extracts derived from hepatic nuclei of prepubescent and mature male and female rats. alpha-Amanitin-sensitive in vitro transcription of the alpha 2u 207 gene by extracts derived from mature male rats is highly active and is at least 13 times as rapid as that with preparations from mature female or immature animals. In contrast, the rate of transcription of a control template, the adenoviral late promoter, is the same with all of these nuclear extracts. S1 nuclease analysis and the size of the transcript indicate that transcription is initiated in vitro at the same site as it is in vivo and that it continues to the 3' terminus of the alpha 2u-globulin template. Thus, cis sequences are present in this gene fragment which are controlled by developmentally regulated male transacting factors, enabling selective transcription of this alpha 2u-globulin gene. Mixing experiments indicate that this transcriptional control is positive.