Abstract: A study of the risk factors associated with Plasmodium falciparum infection in patients attending selected hospitals in Zaria Kaduna State was carried out. Four hundred blood samples were collected by venipuncture from consenting patients. The blood samples were examine microscopically for Plasmodium falciparum on thin and thick blood smears prepared for each sample. The results were analysed statistically using the Chi square test at 95% confidence interval. Only the ring trophozoites of Plasmodium falciparum were observed in the infected samples. Those who were always sleeping under insecticide treated mosquito nets at home had the least prevalence (5.5%) which was lower than the 6.7% prevalence of those who were not sleeping under insecticide treated nets always. The highest prevalence was found among those who were not sleeping under insecticide treated mosquito nets at home with 94.1% (χ2=293.088, p<0.05). Respondents who were using insecticides at home always had the least prevalence with 5.9% the highest prevalence (88.8%) however was found in those not using insecticide at home (p<0.05). Alcohol consumption and smoking were significantly associated with Plasmodium falciparum infection. Smokers had a prevalence of 62.5% which was higher than the 27.6% found in non-smokers. Alcohol users also had a higher prevalence (83.3%) than non-alcohol users with 27% (χ2=9.118, p<0.05). We concluded that consistent use of insecticide and insecticidal nets at home reduced malaria prevalence, while smoking and alcohol consumption increased malaria prevalence due to Plasmodium falciparum infection. In conclusion, alcohol consumption, smoking, use of insecticidal net and insecticides at home were the risk factors found to be significantly associated with malaria infection in this study