Data on the number of illnesses in workers based on the monthly labor force report were evaluated. Beginning in July of 1947, estimates were published monthly concerning the number of employed persons at least 14 years of age who did not work at all the week preceding the survey because they were ill. Comparisons were then made with illness rates in the Armed Forces, seasonal variations of illnesses in civilian populations, and other groups in order to determine any possible trends among the labor force. Between the period of July 1947 and September 1959, the percentages of ill persons ranged between 1 and 2 percent of the work force and there were no overall trends apparent. In general, the fluctuations in the illnesses among the labor force were similar to those in the Armed Forces and a clear impact of influenza epidemics was notable. These epidemics occurred in March of 1950 and 1951, February of 1953, and the Asian influenza epidemic of October and November of 1957. Based on the data gathered in this report, the available man workdays were estimated as 260 per person per year.