Monomorphic lemurs of Madagascar allow us to investigate whether there are behavioural mechanisms that compensate for sex-specific differences in the costs of maintenance and reproduction in arboreal primates. Food selection of the pair-living Lepilemur ruficaudatus was studied in relation to food chemistry, and travel distances were measured as possible indications of differential investment in ranging activities (possibly related to the defence of territories and/or mating opportunities). Fourteen females and 14 males were radio-tracked for a total of 365 half-nights (from dusk to midnight or from midnight to dawn) at different times of the year (birth, lactation and weaning, pre-mating, post-mating). When based on monthly means, the two sexes did not differ in nightly travel distances. Food selection of females and males did not differ in relation to the chemical composition of leaves, but fruits consumed by females had lower fibre contents than fruits consumed by males. Even though other behavioural data are fragmentary, little evidence exists for behavioural mechanisms in L. ruficaudatus to compensate for the different energetic costs of females and males.