We analysed the clinical and laboratory features of 16 males in comparison with 231 females from a series of 247 unselected patients with systemic lupus erythematosus (SLE). There was no significant difference between male and female patients with regard to age at onset and age at diagnosis. Apart from serositis, which was found to occur at a significantly higher frequency in male patients, the incidence of clinical features at disease onset was similar in both sexes. Analysis of clinical findings during the evolution of the disease showed no significant difference between male and female patients. Similarly, no significant immunological difference was found between the two groups. Thus, except for a higher frequency of serositis as the presenting symptom in males, we could not find any notable differences in clinical and serological parameters of male and female patients with SLE.