We examined host preferences and temporal trends of the tick Ixodes angustus on small mammals in north-central Alberta. Small mammals were live-trapped from 1 June to 29 September 1994 and 3 May to 30 June 1995 in mature aspen (Populus tremuloides) forest near Lac La Biche, Alberta. Abundance of female I. angustus was high in early May (0.90 +/- 0.20 [SE]) and peaked again in late June (0.58 +/- 0.16), whereas abundance of immature I. angustus peaked (1.2 +/- 0.35) in mid-July. Red-backed voles (Clethrionomys gapperi) and deer mice (Peromyscus maniculatus) were the most common host species encountered, and tick abundance (number of ticks per animal examined) on these hosts was strongly influenced by species and sex. Clethrionomys gapperi had higher tick abundance (0.73 +/- 0.07) than did P. maniculatus (0.04 +/- 0.01), and ticks were more abundant on large male C. gapperi (0.97 +/- 0.14) than they were on large female C. gapperi (0.36 +/- 0.08; P = 0.0007). Characteristics of each species and sex of host in relation to susceptibility to parasitism are discussed.