Since the approach of the general population to phyto-medicine is that the therapy is natural and therefore safe, the aim of this study was to investigate the relationship between the use of herbal compounds, alone or in combination with traditional drugs, and the occurrence of adverse events among a sample of Italian women. The research was conducted over a 5-month period in the out-patient ambulatories of an urban university general hospital. The sample population consisted of women who were interviewed about phytotherapy use on the basis of a pre-structured questionnaire. Among 1063 women contacted, 1044 completed the interview and 491 (47%) reported taking at least one herbal compound in the last year; of these women 272 (55.4%) consumed only phytomedicines, while 219 (44.6%) also took traditional drugs. Seventy-three different herbal products were used, 32 were consumed in association with traditional drugs. Forty-seven (9.6%) of the 491 women reported adverse events, 22 (8.1%) after taking only phytomedicines, 25 (11.4%) in combination with traditional drugs. The observed adverse manifestations included the following: gastrointestinal after Taraxacum officinale (dandelion), propolis or Foeniculum vulgare (fennel); cardiovascular after Glycyrrhiza glabra (liquorice), ginseng (not specified) and Camellia sinensis (green tea); dermatological after propolis, Thymus vulgaris (thyme), arnica (not specified) and Passiflora incarnata (passionflower); and neurological after guarana and G. glabra (liquorice). Drugs taken in association and potentially involved in adverse reactions were NSAIDs, antibiotics, benzodiazepines, antihypertensives and oral contraceptives. In some cases (n = 5), adverse events were serious enough to justify an admission to hospital.