The daily variations of several medical care activities in a health area of Cuba were evaluated during the first semester of 1990. To this end, chronological series of the different activities were set up, and seasonal indexes were calculated from them. The selected method was the mobile mean, using a multiplicative model as a basis. The occurrence of seasonal changes in the behaviour of evaluated activities was found to be higher in the visits of family physicians in their clinics and in the home visits than in on duty staff. Monday was identified as the least used day. The possible reasons for these results are relate with the schedules of medical tasks and also with population habits. These results may be useful to improve the quality of the health area services.