Objective Fear of deportation (FOD) is a prevalent concern among mixed‐status families. Yet, our understanding of how FOD shapes human health and development is in its infancy. To begin to address this knowledge gap, we examined the relationship between household FOD, body mass index (BMI) percentiles and salivary uric acid (sUA), a biomarker related to oxidative stress/hypertension/metabolic syndrome, among 111 individuals living in Mexican‐origin families. Methods Participants were 65 children (2 months‐17 years, 49% female) and 46 adults (20‐58 years, 71% female) living in 30 Mexican‐origin families with at least one immigrant parent in Phoenix, AZ. We recruited families using cluster probability sampling of 30 randomly selected census tracts with a high proportion of Hispanic/Latino immigrants. The head of household completed a survey containing demographic, FOD, and psychosocial measures. All family members provided saliva (later assayed for sUA) and anthropometric measures. Relationships between household FOD, BMI percentile, and sUA levels were estimated using multilevel models. Results Higher levels of household FOD were associated with lower BMI percentiles and lower sUA levels between families, after controlling for social support and socioeconomic proxies. Conclusion Key features of the social ecology in which mixed‐status families are embedded are associated with individual differences in biological processes linked to increased risk for chronic disease.