Introduction: A pollen pistil extract Sèrèlys (formerly Femal) was reported earlier to alleviate symptoms of premenstrual syndrome (PMS), including sleep disturbances. This paper focuses on previously unpublished effects of the same extract on major PMS symptoms. Methods: 101 women, diagnosed with PMS, were randomly treated with either placebo (51) or Sèrèlys (50) for four (4) months. 50 of the study participants reported irritability as their predominant PMS symptom, while 34 women indicated dysphoria as their main symptom. The remaining volunteers specified several different symptoms as their major concern. Premenstrual tension observer evaluation was performed according to Steiner and the women also gave their personal evaluation scores (Visual Analogue Scale: VAS) of different PMS symptoms including irritability, tender breasts, bloating, retention of water, mood swings, raw luteal phase score and headaches. Results: There were significant reductions in Steiner observer evaluation symptom scores in both groups but no differences comparing groups. In the patients’ self-evaluation there was a significant reduction in headache and water retention as a result of Sèrèlys treatment. When comparing observer-generated Steiner and self-reported VAS symptom scores for patients reporting irritability as their main PMS symptom there was a significant 47% and 50% symptom reduction with Sèrèlys treatment, which was absent in placebo (p < 0.027 and p < 0.001, respectively, comparing groups). By contrast, the dysphoria subset of patients showed no differences when comparing treatment and placebo groups. Conclusion: In patients reporting irritability as their most predominant PMS symptom, Sèrèlys significantly lowered the PMS-indicators, as reflected in both observer and patientś self-evaluation symptoms’ scores.