Injectionsof orange oils with Orange oils, injection of low and high terpene d-limonene, content, d-limonene Murine subcutaneous and intravenous Benzo(rst)pentaphene and a mixture of Carcinogenesis d-limonene and 6% Tumor incidence of its hydroperoxide, were made into the same site of C57BL/6 Jax mice 24 h after subcutaneous injections of 25 μg of dibenzpyrene (DBP) in tricaprylin. This procedure reduced the tumor incidence to less than 50% after 30 weeks (compared with 80% in controls receiving the carcinogen alone or the carcinogen followed by tricaprylin). The time of latency was markedly prolonged. In A mice with spontaneous adenomas and adenomas induced with sc carcinogen, orange oils, as well as limonene, reduced the incidence of lung adenomas when given weekly for from 13 to 16 weeks. The acceleration of tumor growth usually observed following the transfer of multiple pooled carcinogen injection sites into new hosts was inhibited by orange oils