OBJECTIVES: To determine fertility trends in Spain and whether women's specific fertility rates differ by age and nationality during the period 1996-2006. METHODS: We performed a population-based, cross-sectional study. Direct standardization was used to compare fertility rates by nationality. Foreign versus Spanish women's fertility rates by age and the period under review were compared by a generalized linear model. The trend by nationality was described by time plots and was analyzed by simple linear regression models. RESULTS: Foreign women had more children (total fertility rate: 2 versus 1.2) and at younger age. The upward trend observed in the fertility of Spanish women (p<0.001) was primarily due to increased fertility in older mothers (35 years and older). The fertility of foreign women aged < or =19 was six times higher than that of Spanish women (rate ratio: 6.00, 95% CI: 2.60-13.86). CONCLUSIONS: The fertility pattern of foreign women differs from that of Spanish women and is mainly characterized by higher fertility, especially in younger women (< or =19 years). This pattern may be associated with social and cultural differences. Prevention and sexual educational policies should be reformulated to take into account the specific sociocultural characteristics of this group and to adapt prevention messages to their cultural context.