An epidemic of "repetition strain injury" ("RSI") in Telecom Australia is described. In the years 1981-1985, there have been 3976 reports of "RSI". The occupation that was most affected was that of telephonist, with 1886 reports and a rate of 343 per 1000 keyboard staff members over five years; among other occupations that were affected were clerical workers (1421 reports; rate, 284 per 1000 keyboard staff members); telegraphists (17 reports; rate, 34 per 1000 staff members); and process workers (235 reports; rate, 116 per 1000 staff members). Women accounted for 3330 (83%) of all reports; in the telephonist group, 27% of female and 20% of male staff members were affected (P less than 0.001); for women, younger staff members were more affected. There was a significant difference among states in the prevalence of "RSI" in telephonists. There was a high morbidity, and 644 (16%) subjects were affected for more than 26 weeks; the cost-effectiveness of treatment and rehabilitation varied appreciably among state administrations. The costs of the epidemic exceed $15 million, including $1.8 million in medical costs. Reasons for the rise and decline of the epidemic are discussed.