The diet of the European brown bear (Ursus arctos) was studied in the Cantabrian Mountains, Spain, by analyzing the frequency of occurrence and percent volume of 929 feces collected 1983–1988. Plant material was the predominant food during spring and summer (84.1 and 44.8% of total volume, respectively) until more nutritious foods became available. During autumn and winter, hard mast formed the greatest part of the diet constituting 61.5 and 49.9% of the total volume, respectively. Livestock and wild ungulates were supplementary foods for bears, usually obtained by scavenging rather than predation. Insects were consumed year-round, ranging from 19.5% volume in summer to 0.1% in winter. Remnant deciduous forests and upland creek drainages were prime feeding areas of bears.