The study investigates the additional payroll expense caused by absenteeism due to illness among nursing professionals and physicians at two public hospitals at Cacoal, Rondonia, Brazil. Non-programmed absences of up to 15 days which occurred at the hospital units between 2004 to 2007 were verified in the database of the institutions' human resource sector. From 1,704 non-programmed absences, 1,486 were justified by medical declarations.It was verified that absenteeism caused by illness was responsible for 87.2% of all nonprogrammed absences. When these data are grouped by professional categories, it was observed that the nurse absenteeism due to illness reached 83.3%, when compared with 16.7% for physicians. The general absenteeism index, adding up nurses and physicians, corresponded to 0.85%, resulting in an additional payroll expense of 5.2% and 7.4% in the salaries of nursing professionals and physicians, respectively. son justificadas con certificados médicos. Se verificó que el absentismo por motivo de enfermedad fue responsable por 87,2% de las ausencias no programadas. Si fuese descrito por categoría profesional, el absentismo enfermedad de los profesionales de enfermería alcanzaría el índice de 83,3% y el de los médicos 16,7%. El índice de absentismo general de los profesionales de enfermería y médicos fue de 0,85%, en cuanto que el gasto adicional en la planilla de pago en el período alcanzó 5,2% en los salarios de los profesionales de enfermería y 7,4% de los médicos.