This study was aimed to assess oxidative stress, pro-inflammatory cytokines and some trace elements in healthy pet cats exposed to environmental tobacco smoke. Forty healthy cats were included in this study. Cats were divided in two groups: Exposed to tobacco smoke (ETS; n = 20) and non-exposed to tobacco smoke (NETS; n = 20). Blood levels of cotinine, total oxidant status (TOS), oxidative stress index (OSI), lipid hydroperoxide (LOOH), protein carbonyl (PCO), advanced oxidative protein products (AOPP), total antioxidant status (TAS), copper, zinc-superoxide dismutase (Cu, Zn-SOD), catalase (CAT), total thiol (T-SH), interferon gamma (INF-γ), tumor necrosis factor (TNF-α), interleukin β (IL-1β), interleukin 6 (IL-6), interleukin-8 (IL-8), interleukin 2 (IL-2) and iron (Fe), zinc (Zn), copper (Cu), selenium (Se) levels were measured. Hematological and biochemical parameters were also measured. Serum cotinine, TOS, OSI, PCO, AOPP and LOOH levels were higher, whereas TAS and Cu, Zn-SOD levels were lower in ETS group. In ETS group INF-γ, IL-1β, IL-2, and IL-6 levels were higher. The Cu level was higher in ETS group. Blood reticulocyte number, serum creatinine and glucose were higher in ETS group. It could be concluded that exposure to tobacco smoke in cats impaired the oxidant/antioxidant balance and potentially triggered the release of pro-inflammatory cytokines.