The yield on the 30-year Treasury bond ended lower on Monday, while yields of shorter-maturity issues rose.
Market participants said technical factors were behind the long bond's slight fall.
The 30-year bond yield was 6.55% late Monday afternoon, down from 6.56% on Friday.
The 10-year note yield was 5.84%, up from 5.80% Friday, and the five-year note yield was 5.21%, up from 5.14% Friday.
The dollar was lower on Monday afternoon from its Friday levels. It had hit a postwar low against the Japanese yen of 104.14 before rising slightly.
Traders said the yen's strength reflected its place as a safe haven from continuing tensions in the European monetary system.
The dollar also fell to 1.70 German marks on Monday afternoon, from 1.7415 marks late Friday.
The Dow Jones industrial average rose 21.52 points, to, close at 3560.99.
Stocks were buoyed by expectations of lower European interest rates.