The B-series are a family of inline four-cylinder DOHC automotive engines introduced by Honda in 1988.

Sold concurrently with the D-series which were primarily SOHC engines designed for more economical applications, the B-series were a performance option featuring dual overhead cams along with the first application of Honda's VTEC system (available in some models), high-pressure die cast aluminum block, cast-in quadruple-Siamese iron liners.

[2] The B-series, the B20B variant in particular, is not to be confused with the earlier Honda B20A engine introduced in 1985 and primarily available in the Prelude and Accord-derived vehicles from 1985 to 1991.

While sharing some design elements and both being multivalve Honda four-cylinders, the B-series and B20A differ substantially in architecture, enough to be considered distinct engine families.

The original Japanese B18A is not considered to be part of the modern B-series family, although it shares its dimensions with the later B18A1.