I calculated the relationship between instantaneous natural mortality,M(d–1), and dry body weight,W(μg) for herring larvae and adults using data from the scientific literature. Geometric mean mortality of adult Pacific herringClupea pallasi(0.52·year–1) was about three times greater than that of adult Atlantic herringClupea harengus(0.18·year–1), which may reflect greater reproductive effort per unit size by Pacific herring than by Atlantic herring. Geometric mean mortality of Pacific herring larvae (0.083·d–1) was 30% greater than that of Atlantic herring larvae (0.064·d–1), but the difference was not significant. The functional regression for Atlantic herring was loge(M) = –0.4924 – 0.4064·loge(W), and the regression for Pacific herring was loge(M) = 0.1553 – 0.3935·loge(W). The regressions provide preliminary estimates of averageMof herring eggs and juveniles, life history stages for which there are few direct estimates of mortality. They also indicate that the weight exponent of instantaneous growth of herring should be greater than –0.4. Allometry of herring mortality implies that year-class strength of herring should be positively correlated with size at recruitment.