Long-term manure application could increase soil earthworm abundance in cultivated soils. The objective of this study was to evaluate the effect of 14 yr (1977–1991) of manure and NPKMg fertilizer on earthworm populations, soil structural stability, N mineralization (NO3) and biological activity (CO2) on a Le Bras clay loam (Humic Gleysol) situated at St-Lambert, Quebec. The field experiment, in a split-plot design, consisted of two manure rates (0 Mg, 20 Mg ha−1) as principal treatments with secondary treatments receiving mineral fertilizer (NPKMg) and a control. These treatments were carried out over a 4-yr crop rotation of silage corn, (Zea mays L.), wheat (Triticum aestivum L.), barley (Hordeum vulgare L.) and canola (Brassica campestris L.). Soil and earthworm sampling was done in fall 1991 under corn. Compared to mineral fertilizer treatment, long-term application of manure increased earthworm populations. However the interaction between the treatments of mineral fertilizer and of manure was not significant. Of the earthworms extracted by formalin and hand sorting, Aporrectodea genus was dominant in soil, representing 98–100% of the population. Several Allolobophora chlorotica and Lumbricus juveniles from the genus Lumbricus were found only in manured plots. Soil water stable aggregates and biological activity (CO2) were both increased by manure application. Mineral fertilizer application had no significant effect. A strong correlation was obtained only between earthworm abundance and biological activity (CO2). The results indicate that 14 yr application of solid cattle manure improved soil earthworm populations and diversity, biological activity (CO2) and structural stability compared to fertilizer treatments and the control. Key words: Earthworms, Aporrectodea turgida, manure, mineral fertilizer, organic matter, biological activity (CO2), N mineralization potential (NO3), water-stable aggregates