It has been well documented that immigrants' clustering of residence in large cities has been associated with the creation of a number of ethnic enclaves. The intensive exposure to own-ethnic population could affect immigrant labour market involvement positively or negatively. However, no extant Canadian research has provided empirical evidence on the sign of these enclave effects. In this paper, I use the 1981-2001 Censuses to estimate the impact of residence in ethnic enclaves on male immigrants' labour force participation rate and employment probability. For recent immigrants who arrived in Canada within the preceding ten years, the intensity of enclave residence is negatively associated with their labour force participation rate, but positively related to their employment probability in all censuses. However, living in an enclave has no significant effect on the labour force activity of older immigrants who have lived in Canada for more than twenty years. Since immigrants could be attracted to areas with more job opportunities and hence enlarge the size of an enclave, the estimated effects from probit regressions might be positively biased. I then use instrumental variable (IV) method to address this endogeneity problem, and the IV estimates are consistent with the probit regression results.