This paper presents theoretical and practical implications of sampling application in internal audit processes. Sampling is the process of testing a portion of a population and drawing conclusions about the entire population based on the obtained results. In modern times, sampling in internal audit processes remains a necessity due to the large number of units that may constitute the population and the lack of sufficient time and resources to conduct testing based on the entire population. Internal auditors can use both non-statistical and statistical sampling, as well as methods such as haphazard sampling, random sampling, block sampling, and interval sampling. Additionally, the application of certain sampling methods can be supported by PPS (Probability Proportional to Size) techniques and stratification. The choice of sampling methods depends on factors such as population characteristics and the audit objective, and the adequacy of the sampling method choice affects the reliability of audit evidence. The methods and techniques of sampling presented in this paper can assist internal auditors in implementing sampling in the processes of conducting control and substantive tests.