This report, the fourth in a series, analyzes gin operating costs in West Texas for the 1969-70 season. The gin sample from which these data were obtained was stratified, by rated hourly capacities, into four size groups. Cost comparisons by size groups are made, for this and last season, using several different costing methods. Average costs for two size groups are compared with cost estimates for synthesized model gins of comparable sizes. A 5-year comparison of average costs for all groups combined is shown.