In this study, Casuarina equisetifolia needles were evaluated as the possible biomonitors of heavy metal air pollution in Mascara (Algeria). The needles were sampled from seven locations with different degrees of metal pollution (near roads) and from a control site. The concentrations of lead, zinc, copper and nickel were measured by using a flame atomic absorption spectrophotometer. The maximal values of these four metals were found in the samples collected near the roads and the minimal values were found in the control site. Furthermore, sites with high traffic density and frequency of cars stoppage showed high heavy metal concentrations. However, the comparison of concentrations of all metals showed that the zinc one had the highest concentration of all. The cluster analysis divided the selected sampling sites in three distinct clusters. With regard to the results of this study, Casuarina equisetifolia can be successfully applied in biomonitoring of air pollution.