Background & Objectives: Pain is one of the most common problems for which human have always been looking for efficient treatment. Several different factors may cause pain, but one of the most widespread reason is the application of some treatments and nursing measures such as intramuscular injection. The present study was designed to compare between the intensity of pain due to intramuscular injection by two different methods: Z- track and Air lock method.

  Methods: In this semi-experimental study, 60 volunteer female nursing students were included. The subject was injected with one milliliter of sterilized water two times within 24 hours: the first injection by Z method and the second one by the Air lock method. The intensity of pain was measured two times by a scale graded from zero to ten. The results were compared by using descriptive statistics and independent t-test by SPSS 12 software.

  Results: Our findings showed that the mean of pain intensity in Z method was 1.80 ± 1.90, and raised to 3.13 ± 2.33 in Air lock method. Moreover, the intensity of pain in these two different methods had significant difference (p<0.01).

  Conclusion: These results indicated that the pain caused by Z method is less than the pain felt through Air lock method. With respecting to these results the Z method is proposed as preferred method for intramuscular injections.