This study was to investigate the influence of housing system on lamb puberty. Forty- eight Farafra ram lambs with an average weight of 19 kg and 4-5 months of age were used during summer. Ram lambs were randomly divided into six groups and housed under six housing systems, they are differed mainly in the type and height of roofs, as follow: 1) Semi open type house shaded with asbestos sheets (AS); 2) Semi open type house shaded with straw earth floors (S); 3) a close type shaded with single asbestos roof at 3 m height (single low type, SL); 4) a close type shaded with single asbestos roof at 5 m height (single high type, SH); 5) a close type shaded with double asbestos roofs at 3 and 3.5 m height for two roofs, respectively (double low type, DL); 6) a close type shaded with double asbestos roofs at 5 and 5.5 m height for two roofs, respectively (double high type, DH).. The experiment period lasted for 5-6 months. Ram lambs were tested for libido (first mounting without erection, first mounting with erection and first collected ejaculate containing motile sperm, puberty) at 8:00 am to 9:00 am daily until puberty. Testis measurements, scrotal circumference, testis length, and volume of the testes were recorded monthly during the experimental period. Age and weight at first mounting without erection, first mounting with erection and age at first collected ejaculate containing motile sperm (puberty) was recorded. Blood samples were collected for determination of serum testosterone. All results were analyzed using GLM procedure of SAS. Average age and weight of growing ram lambs at first mounting without erection, at first mounting with erection and at first ejaculation with spermatozoa (puberty) were (199.08 days and 26.42 kg), (250.92 days and 33.00 kg) and (288.00 days and 37.29 kg), respectively. Among puberty stages, ram lambs in closed houses (DL and DH) had significantly lower age at first mounting without erection than that in semi open types (AS and S). Also, ram lambs in closed houses had significantly lower age at first mounting with erection and age at puberty than those in semi open one. Ram lambs in closed houses had significantly higher testicular volume, right and left testis length and scrotal circumference means than those in semi open one. With the advancement of age, ram lambs in closed houses had significantly higher testicular volume, right and left testis length and scrotal circumference means than those in semi open one. Serum testosterone levels of ram lambs increased gradually with advancing of age until attainment of puberty (369.56 ng/dl). Ram lambs in closed houses had higher average serum testosterone levels than that in semi open houses (AS and S). Among puberty stages, housing systems had no significant effect on serum testosterone levels of ram lambs in the first mounting stage. Whereas, in the first mounting with erection stage, and in the first ejaculation (puberty) serum testosterone levels of ram lambs were significantly higher in closed houses than those in semi open one. In conclusion, closed houses, particularly that with high and double roof during hot months may enhance puberty of ram lambs