This study aims to analyze, in mice, the long-term effects of delayed fatherhood on postnatal development, spontaneous motor activity, and learning capacity of offspring. Hybrid parental-generation (F₀) males, at the age of 12, 70, 100, and 120 wk, were individually housed with a randomly selected 12-wk-old hybrid female. The resulting first-generation (F₁) offspring were tested for several developmental and behavioral variables. Cumulative percentage of F₁ pups that attained immediate righting in the 120-wk group was lower than that found in the 12-, 70-, and 100-wk groups. Furthermore, the postnatal day of attaining immediate righting was higher in pups from the 120-wk group when compared to pups from the other age-groups. At the age of 20 wk, F₁ offspring from the 120-wk group displayed lower counts of motor activity than offspring from the 12-, 70-, and 100-wk groups. One week later, a higher percentage of offspring from the 100- and 120-wk groups entered the dark compartment during the retention trial of the passive-avoidance test when compared to offspring from the 12-wk group. Offspring from the 120-wk group exhibited also lower step-through latency in the retention trial than offspring from the 12-, 70-, and 100-wk groups. These results show that advanced paternal age at conception has long-term effects on preweaning development, spontaneous motor activity, and reduced passive-avoidance learning capacity of mouse offspring.