The pharmaceutical needs of 79 patients in two private nursing homes of good average standard have been assessed. A set of instruments has been devised and used to evaluate the prescribing of medicines in terms of patient diagnoses, health status and the patterns of medicine administration. Following the collection and analysis of baseline data, a number of recommendations for changes were made to the GPs and the nursing staff. Five further medication reviews were made at monthly intervals and additional recommendations made. The acceptance and implementation of all recommendations and their outcomes were determined. A total of 52% of all recommendations were accepted, though this differed in each nursing home. Some of the barriers to success in effecting these changes were identified. Over the course of the study, there was a mean reduction in prescribing equivalent to 1.5 items per patient. In Nursing Home 2 there were significant differences in the prescribing of drugs for the alleviation of both constipation (P<0.006) and skin treatment (P<0.006) on an 'as required' basis. In Nursing Home 1, there were significant improvements in the patterns of medicine administration (P<0.05) by nursing staff. The prescribing of skin preparations appeared to rise overall by 3%, mainly due to the improved accuracy of recording these treatments. In both nursing homes, observed improvements in the health status of the patients included significant decreases in the incidence of health problems (P<0.05), pressure sores (P<0.05) and constipation (P<0.005). Following consultation with nursing staff, guidelines were agreed which formalised a protocol for the prescribing and administration of laxatives; and the discretionary use by nurses of wound care products. The mean time involvement by the pharmacist to initiate and continue the process of monthly medication review on an individual patient basis is estimated at 1.4 hours and 8 minutes respectively.