This is a descriptive study of nursing practices in nosocomial infection control (NIC) in Spain. During the period 1990-1991, a questionnaire, adapted from that used in the Study on the Efficacy of Nosocomial Infection Control (SENIC), was mailed to all Spanish general hospitals, public and private, having more than 400 beds, and to all those in the public health sector having more than 100 beds. Nursing-related information was selected for analysis from each of three sections: staff, surveillance systems and programmes. The response rate was 70%. While nursing resources allocated to NIC in Spain registered an overall ratio of nosocomial infection control nurses (ICNs) of mean 0.45, SD 0.71 ICN per 250 hospital beds, ICN/beds ratios were below 0.34 and 0.30 in medium-sized and large hospitals respectively. Nurses who were active in NIC were either lacking or worked only a few hours per week in a considerable proportion of hospitals, with this trend being more pronounced in smaller facilities. The intervening period since 1965, and the last decade in particular, has been marked by the progressive adoption of a range of NIC policies. Most procedures proving NIC-efficient had been implemented in approximately 70-80% of responding hospitals. Teaching was most qualified and intensive in medium-sized hospitals. Nursing in NIC has only recently been developed in Spain, is increasingly accepted, exhibits diffusion levels comparable to those reported internationally, lacks monitoring and quality assessment systems and, in general, could be substantially improved.