Objective To investigate the prevalence and risk factors of Toxoplasma gondii infection among key populations in Wuxi City,Jiangsu Province,so as to provide evidences for developing preventive and control interventions for T. gondii in-fection. Methods A questionnaire was designed to conduct face-to-face interviews to HIV/AIDS carriers/patients,tumor pa-tients,pregnant women and pet breeders. The blood samples were collected to test anti-Toxoplasma IgM and IgG antibodies by using ELISA method. Results Totally 404 participants were investigated,and 38 were positive in testing T. gondii antibodies (9.4%),and among these,37(97.4%)were IgG positive and 1(2.6%)was IgM positive. The multivariate logistic regression indicated that age,regularly contacting cats/dogs and being HIV positive were associated with the infection of T. gondii(OR=2.1,2.6 and 2.3,all P < 0.05). Breeding pets,being HIV positive and being tumor patients were more likely to infect T. gondii than being pregnant(OR = 1.5,8.1 and 2.8,all P < 0.05). Conclusion The high infection rate of T. gondii is observed among key populations in Wuxi City,so that the effective measurements should be taken to enhance the intervention among key popula-tions including immunocompromised people,pet breeders or people having bad dietary habits of eating raw food.