[en] Preliminary results of outdoor gamma radioactivity measurements, specific activities of radionuclides in the soil and indoor radon concentrations in Tenerife (Canary Islands) are presented here. The results were obtained using GM MC-71 detectors, HPIC RSS-112, intrinsic Ge detector, charcoal canister and etched track. Outdoor gamma radioactivity levels were determined in each of 103 sites into which the island was divided up. A soil sample was taken at each site to determine concentrations of ^226Ra, ²³²Th and ⁴⁰K. The charcoal canisters were placed for 3 days in dwellings located in the most densely populated areas of the island. In 13 dwellings etched track detectors were also placed for 3 months. The mean gamma radioactivity level was 67 nGy.h^-1. Specific activities of ²²⁶Ra, ²³²Th and ⁴⁰K were 44 Bq.kg^-1, 54 Bq.kg^-1 and 665 Bq.kg^-1, respectively. The median values for radon concentrations were 58 Bq.m^-3 (etched track) and 37 Bq.m^-3 (charcoal canisters). A thorough survey of environmental radioactivity in the Canary Islands archipelago is to be undertaken. (author)