Five of the genes known to encode the enzymes for the synthesis of poly(glycerol phosphate), the major teichoic acid of Bacillus subti/is 168, are organized in two divergently transcribed operons, tagAB and tagD€F. lacZ and gus transcriptional fusions to the first genes of these operons revealed that: (i) in media of different richness, higher growth rates were paralleled by lower transcription levels; (ii) upon transition to stationary phase, the transcription per unit mass of both operons increased abruptly by a factor of about two;and (iii) a rise in temperature was accompanied by decreased transcription of tagA and increased transcription of tagD. Mapping of transcription start points revealed two divergent aA-controlled promoters. Although tagD and the neighbouring downstream gene tag€ are transcribed from the same promoter, the latter was expressed at a much lower level than the former. Moreover, expression of tag€, and of the translationally coupled tagF, did not increase at the onset of the stationary phase, indicating that additional regulatory signals may act in the intergenic tagD-tag€ region. Optimal transcription of these operons appears to require the entire regulatory region, suggesting that tag gene expression may, among other factors, be regulated by the threedimensional configuration of this segment. The biological implications of these results are discussed.