In 1982 physicians at a hospital melanoma clinic in Montreal noticed that among their patients there had been seven men working in a single telecommunications company. This raised suspicions that working in that industry might be associated with development of malignant melanoma of the skin (MMS). A preliminary gross comparison with general population rates indicated that there was an increased risk in this working group. To estimate the risk of MMS more accurately, a standardised incidence ratio (SIR) was calculated based on the rates of MMS in the local population of the Greater Metropolitan Montreal Area for the years 1976-83. During that period, among workers in all plants for the company, 10 male cases of MMS were observed for an expected number of 3.7 (SIR = 2.7; 95% CI = 1.31-5.02). No cases were observed among female workers (expected = 1.3). The excess was significant among cases with a short latency (less than 20 years since beginning of employment). There was no apparent pattern of exposure based on job titles or departments.