Infections, especially those of the respiratory system, are very common in children from areas with high air pollution, and the incidence of infections is even greater in the case of immature immune system. Zinc plays an important role in the regulation of innate and acquired immune response. This element is involved in the production of proteins, wound healing, DNA synthesis and cell division, and is essential in the development and activation of T cells. Zinc deficiency disrupts phagocytosis, intracellular killing and cytokine production by macrophages. The aim of the study was to assess serum zinc levels in children with recurrent respiratory infections from the Łódź region, diagnosed at the Department of Paediatrics and Allergy in Korczak Paediatric Centre. Materials and methods: The study included 60 children with recurrent infections (≥6 respiratory infections over 6 months) and 60 healthy children aged 1–18 years. Flame spectrometry was used to measure serum zinc levels in all patients. Results: Nearly 40% of children with recurrent infections had low serum zinc levels (<70 μg/dL). There were no statistically significant differences in zinc levels depending on sex. Multivariate analysis showed significant differences in serum zinc levels between the control group and the group with recurrent respiratory infections (p = 0.044). Conclusions: The obtained results indicate that zinc deficiency is frequent in children with recurrent respiratory infections from the region of Łódź.