Aim: To study the effect of the title drugs on the serum FSH, LH andtestosterone (T) levels in Chinese men in a contraceptive trial. Methods:Sixteen male volunteers were administered Chinese-made implant (tworods, each containing 75 mg of levonorgestrel, LNG) plus testosterone un-decanoate (TU) (250 mg, i.m. monthly for3 months). FSH, LH and Tlevels were determined with RIA. Results: The serum FSH and LH lev-els declined after the insertion of implants. They declined further after the1st TU injection and one week later, both FSH and LH levels reached thelowest levels, after which, they rose slightly. The profiles of serum LH andFSH levels after the 2nd and 3rd TU injection were similar to that followingthe 1st TU injection. After insertion of the implants, the serum T levels alsodeclined. However, after the 1st dose of TU, the T levels increased, oneweek later they reached the peak level, and then declined again. The pro-files of serum T levels after the 2nd and 3rd TU injection were also similarto that Aim: To study the effect of the title drugs on the serum FSH, LH andtestosterone (T) levels in Chinese men in a contraceptive trial. Methods: Sixteen male volunteers were delivered Chinese-made implant (tworods, each containing 75 mg of levonorgestrel, LNG) plus testosterone un-decanoate (TU) (250 mg, im monthly for 3 months). FSH, LH and Tlevels were determined with RIA. Results: The serum FSH and LH lev-els declined after the insertion of implants. After the1st TU injection and one week later, both FSH and LH levels reached the lowerest levels, after which, they rose slightly. The profiles of serum LH andFSH levels after the 2nd and 3rd TU injection were similar to that followingthe 1st TU injection. After insertion In the implants, the serum T levels alsodeclined. However, after the 1st dose of TU, ​​the T levels increased, oneweek later they reached the peak level, and then causing confidence again. The pro-files of serum T levels after the 2nd and 3rd TU injection were a Lso similarto that