Abstract: The EU guarantees the free movement of persons. The citizens of the EU Member States have the right to move freely without barriers within the EU borders and this result in an integration of the peoples in Europe. The integration result in several international family relationships. It is not unusual in the present situation that families have international relations. For example, spouses in a married couple may have different nationality. The international family law in Europe is applicable in case of a cross-border family dispute. The international family law consists of specific common rules on jurisdiction and rules on recognition and enforcement of judgments. There is no substantive family law or conflict-of-law rules in the international family law in the present situation. National law regulates the substantive law and the conflict-of-law rules. Since all Member States applies its own substantive family law, and the fact that national family law rules may differ in many cases, the absence of a common substantive family law in the EU cause issues in international family law. The differences in the substantive family laws affect citizens negatively in case of one Member State imposes less favorable legal effects compared to the internal law of another Member State. The national conflict-of-law rules apply since the international family law does not include any conflict-of-law rules. The conflict-of-law rules identifies the applicable national substantive law which gives rise to the problems in cross-border disputes. The international family law has no substantive solution to the cross-border disputes. The issues in international family law are that EU citizens are not necessarily treated the same way in all Member States even if the circumstances in a family law situation are identical. Legal uncertainty, risk of discrimination on grounds of nationality and possible obstacles to the free movement of people in the EU are examples of how citizens are affected by the divergences in international family law in the EU. A harmonisation of substantive family law is required to meet the citizens' rights under similar conditions in all Member States. However, the EU should not strive for common conflict-of-law rules since these rules only specify the substantive law. Differences in judicial practice arise in the substantive family law. A harmonised substantive law in the EU is required to avoid such differences. A harmonisation of these rules is complex due to the differences in national law. For example, the differences in the substantive law give rise to difficulties to harmonise the substantive rules by means of regulations. An appropriate solution for the harmonisation of substantive law is to let the Court of Justice of the European Union and the literature achieve a harmonised international family in Europe in due time.