A study to assess the effectiveness of muscle stretching exercises on pain and discomfort during primary dysmenorrhoea among BSc nursing in a selected college of nursing at Kannur”. One group pretest and posttest design was adopted. Setting of the study was crescent College of Nursing, Kannur. Sample was 50 BSc Nursing students with primary dysmenorrhoea. Sampling technique was Non probability purposive sampling technique. The model of this study was developed from Titler et al (2004) Effectiveness model. Menstrual pain perception level was measured by using numerical pain scale and primary dysmenorrhoea discomfort was assessed by primary dysmenorrhea discomfort assessing rating scale. Muscle stretching exercise was given to the subjects five days per week about 30 min, under the supervision of investigator. Result of the study had shown significant effect of muscle stretching exercises on pain and discomfort during primary dysmenorrhoea. This is proved by paired‘t’ test. The paired‘t’ value for pain and exercise was16.09 (p<0.05) and the paired‘t’ value for discomfort during primary dysmenorrhoea and exercise was14.08 (p<0.05).So it was statistically proved that muscle stretching exercise was effective to reduce pain and discomfort during dysmenorrhoea.