Abstract
Background: The naturally occurring fluctuations in the levels of sex steroid hormones during the menstrual cycle provide a convenient basis for analyzing the interactions between sex steroid hormones and immune mechanisms. The study estimated total leukocyte count (TLC) in different phases of menstrual cycle.

Aims and Objective: The aim was to study the variations in TLC in three phases of menstrual cycle.

Materials and Methods: The study comprises 100 girls aged between 18 and 25 years. Venous blood sample (2 ml) was collected under aseptic precautions during a single cycle in three phases of their menstrual cycle: on 2nd day, 11th day, and 21st day. Assessment of TLC was done using an automated hematology analyzer.

Results: Significant changes were observed in TLC, during the three phases of menstrual cycle and more so during the secretory phase of menstrual cycle, which is probably due to the hormonal changes during the luteal phase.

Conclusion: The study on changes in leukocyte counts during the menstrual cycle has indicated that there are cyclical fluctuations in the TLC over the course of the menstrual cycle, and the immune response is influenced by changes in hormone status.