Background. It is difficult to measure and compare workload in UK general practice. A GP/health economist team recently proposed a means of calculating the unit cost of a GP consulting. It is therefore now possible to extrapolate to the costs of other clinical tasks in a practice and then to compare the workloads of caring for different patients and compare between practices. Objectives. The study aims were: (i) to estimate the relative costs of daily clinical activities within a practice (implying workload); and (ii) to compare the costs of caring for different types of patients categorized by gender, by age, and by socio-economic status as marked by the Council Tax Valuation Band (CTVB) of home address. Methods. The study design was a cross-sectional cost comparison of all clinical activity aggregated, by patient, over one year in an English semi-rural general practice. The subjects were 3339 practice patients, randomly selected. The main outcome measures were costs per clinical domain and overall costs per patient per year; both then compared by gender, age group and by CTVB. Results. CTVB is as significant a predictor of patient care cost (workload) as is patient gender and age (both already known). Conclusions. It is now possible to estimate the cost of care of different patients in such a way that NHS planning and especially resource allocation to practices could be improved.