The Swiss National Bank (SNB) has conducted sealed-bid, uniform-price auctions for allocating T-bills on behalf of the Treasury since July 1979. This study describes the development of auction rules and summarises the results in terms of bidders' behaviour and auction outcomes. From July 1979 to December 2020, the SNB held 1,634 auctions, all well covered. T-bills have been a stable and reliable source of funding for the treasury through which it borrowed CHF 1.121 trillion. There is clear evidence of a marked increase in the demand for T-bills by private investors following the introduction of noncompetitive bids, sustained broad-based interest despite a steady decline in yields since the 1990s, an extraordinary demand boost after the global financial and European sovereign debt crises, and net revenue from T-bill borrowing of CHF 502 million.