Measurements of the dose rate changes were carried out in order to assess seasonal and spatial radioactivity variations in the largest limestone cave of the Polish Jura Wierzchowska Górna. Thermoluminescence detectors, which were annealed, calibrated and protected against humidity were used. Measurements were repeated four times in 13 locations to observe possible changes. The external dose rate was in the range of 0.004-0.106 mGy/quarter. The results were influenced by the detector locations - lower doses were estimated closer to the cave entrance and the highest doses were in the so-called 'primitive man room'. Doses measured in four periods were statistically significantly different. The external dose level as well as seasonal and spatial dose changes measured in the cave were low. In other caves where external doses are higher, seasonal and spatial dose changes may have a stronger impact on radiological hazard.