This paper uses 1977 data from a national probability sample of 1,200 hospitals to estimate the effect of unions on wages and fringe benefits in four occupations: registered nurses, practical nurses, secretaries, and housekeepers. The results show that unionization has a significant impact on wages that increases with the length of time collective bargaining has been in effect at the individual hospital. The overall wage effect of unions is about 8 percent for both types of nurses and 11 to 12 percent for secretaries and housekeepers employed in hospitals. The authors also estimate an equation for hospital wide fringe benefits, which shows that such benefits are positively related to the percent of full-time employees in the four occupations covered by union contracts.