Potato tubers were examined in a field experiment conducted over the years 2004-2006 and arranged as a split-plot design with three replicates. Two factors were studied: I – three mid-early cultivars of edible potato: Wiking, Mors, Żagiel; II – six methods of Colorado beetle control: control (without application of chemicals), Actara 25 WG (0.08 kg ha–1), Regent 200 SC (0.1 dm3 ha–1), Calypso 480 SC (0.05 dm3 ha–1), Calypso 480 SC (0.075 dm3 ha–1) and Calypso 480 SC (0.1 dm3 ha–1). Potassium content was determined in the dry matter of potato tubers following wet mineralization and using atomic absorption spectrophotometry (AAS). Phosphorus was determined by means of the photometric method. The objective of the study was to examine the effect of insecticides used to control Colorado beetle on phosphorus and potassium content in potato tubers. Most potassium was found in the tubers of Mors – 27.19 g kg–1 on average, significantly less in Wiking – 25.14 g kg–1 on average, and the least in Żagiel –23.67 g kg–1 on average. The highest and lowest phosphorus concentrations were determined in, respectively, Mars (3.490 g kg–1 on average) and Wiking (2.910 g kg–1 on average). Application of insecticides resulted in a significant increase in potassium and phosphorus content in tubers, which ranged from an average of 0.15 to 0.61 g kg–1 for potassium and 0.059 to 0.118 g kg–1 for phosphorus, compared with the control. Our analysis of the influence of atmospheric conditions on phosphorus content in potato tubers demonstrated that the highest phosphorus levels, 3.563 g kg–1 on average, were determined in 2006, which was characterized by the highest precipitation and temperature. The lowest potassium accumulation in potato tubers was recorded in 2004, 2.897 g kg–1 on average.