Migration is an integral part of the globalization process and represents a challenge to the modern way of life. The year 2015 was marked by mass migration towards the Member States of the European Union, while the migrant surge prompted by perennial transition processes in the Middle East and North Africa within the so-called “Arab Spring”, affected also Croatia, which found itself on so-called “Balkan Migrant Route”. Human migration, particularly the migrant crisis, leads to increasing crime rates, and as well to appearance of new forms of crime. Therefore, the aim of this paper is to address the terms and causes of illegal migration, furthermore illegal migration routes, international and domestic legal framework on migrant smuggling, essential elements of the related criminal offence and its aggravating forms, and lastly the case law and sentencing policy in response to the current migrant crisis. Trafficking in human beings has certain similarities, but also differences in relation to migrant smuggling, however, these are criminal offences that are often of an international character; accordingly the specifics and differences of these offences are also presented in the paper. In order to give a better insight into the issue of illegal migration as punishable acts, the paper analyses statistical data at a four-year level (from 2016 to 2019) in respect of structures of offenders committing the criminal offence of illegal entry, movement or residence in the Republic of Croatia, another Member State of the European Union or a Signatory to the Schengen Agreement, prescribed in Article 326 of the Criminal Code/11, the offenders' modus operandi, structure of competent state attotneys' and courts' decisions and criminal sanctions regarding the offence in question.