Reduced salivary secretion can produce a wide variety of complaints, having a negative impact on the daily life of a patient. Multiple causes of salivary hypofunction are described, however, there are no consistent data about the influence of clinical parameters on parotid gland function. We studied a group of patients with head and neck malignancies before treatment with radiotherapy. We used Lashley cups to collect stimulated parotid saliva simultaneously from both parotid glands. Sizes of the parotid gland, gender, age, tobacco and alcohol consumption, and tumour characteristics were related to the function of the parotid gland. A considerable variability in parotid output was found with a range of 0.03-1.66 ml/min (mean 0.34 ml/min). None of the variables were correlated with parotid flow. These results are important, especially when evaluating effects of radiation on parotid gland function.