In the past 30 years Denmark has experienced immigration from non-Western countries, but little is known about immigrants' use of health care. The purpose of this study was to compare and quantify the contact patterns with general practice and casualty departments of immigrants of non-Western origin and non-immigrants in Copenhagen City, Denmark. Descriptive register-based study including 2,041,454 daytime contacts in general practice, 202,179 out-of-hours services and 112,733 attendances to casualty departments by 423,201 inhabitants living in Copenhagen throughout 1998. The data was analyzed using Poisson regression models. Immigrants and non-immigrants showed in broad outline the same sex and age-related pattern of contact except for ages above 60 years, where the pattern was more inconclusive. Children of immigrants aged 1-18 years had lower contact rates than non-immigrants during the daytime and in the out-of-hours services/casualty departments. Most immigrant groups aged 19-59 years made greater use of both daytime and out-of-hours services/casualty departments, especially males from Lebanon and the stateless, than non-immigrants, but the level of contact rates varied according to country of origin. The share of telephone consultations in the daytime and the out-of-hours service was much lower for immigrants than for non-immigrants. Marked differences between immigrants and non-immigrants' use of health care services were related to age and country of origin. More research is needed to explain these findings.